CN112094637A

CN112094637A - Quantum dot, composite including the same, and display device including the same

Info

Publication number: CN112094637A
Application number: CN202010560246.XA
Authority: CN
Inventors: 金泰坤; 田信爱; 金泽勋; 杨惠渊; 元那渊; 李钟敏; 林美惠
Original assignee: Samsung Electronics Co Ltd
Current assignee: Samsung Display Co Ltd
Priority date: 2019-06-18
Filing date: 2020-06-18
Publication date: 2020-12-18
Also published as: US11352558B2; EP3753996A1; US11788005B2; KR20200144510A; US20200399536A1; US20220298413A1

Abstract

Disclosed are a quantum dot, and a composite and a display device including the same. The quantum dot comprises a semiconductor nanocrystal core comprising indium and phosphorus, and a semiconductor nanocrystal shell disposed on the semiconductor nanocrystal core, the semiconductor nanocrystal shell comprising zinc, selenium, and sulfur, wherein the quantum dot does not include cadmium, wherein the quantum dot has a maximum photoluminescence peak in a green light wavelength region, wherein a ratio a of an absorption value at 450nm to an absorption value at a first absorption peak in an ultraviolet-visible (UV-Vis) absorption spectrum of the quantum dot₄₅₀/A_firstGreater than or equal to about 0.7, and a Valley Depth (VD) defined by the following equation is greater than or equal to about 0.4: (Abs)_first‑Abs_valley)/Abs_firstVD wherein Abs_firstAnd Abs_valleyAs defined in the specification.

Description

Quantum dot, composite including the same, and display device including the same

This application claims priority and all benefits derived therefrom from korean patent application No. 10-2019-0072494, filed in the korean intellectual property office at 18.6.2019, the contents of which are incorporated herein by reference in their entirety.

Technical Field

Disclosed are Quantum Dots (QDs), compositions or composites including the quantum dots, and electronic devices (e.g., display devices) including the quantum dots or composites including the quantum dots.

Background

Unlike bulk materials, quantum dots (e.g., nano-sized semiconductor nanocrystals) have an energy bandgap that can be controlled by adjusting the size or composition of the quantum dot. The quantum dots may exhibit electroluminescent and photoluminescent properties. Quantum dots can be prepared by colloidal synthesis, and organic materials such as dispersants can coordinate (e.g., bind) to the surface of the semiconductor nanocrystal during crystal growth to provide quantum dots of controlled size and with desired light emitting properties. Finally, from an environmental point of view, it is desirable to develop a cadmium-free quantum dot having improved photoluminescence properties.

Disclosure of Invention

Embodiments provide an environmentally-friendly quantum dot that is substantially cadmium-free, which may exhibit improved photoluminescence properties and enhanced stability (e.g., thermal stability).

Embodiments provide a method of manufacturing the above quantum dot.

Embodiments provide a composition comprising the above-described quantum dot.

Embodiments provide a quantum dot-polymer composite including the above quantum dot.

Embodiments provide an electronic device including the above quantum dot.

Embodiments provide a layered structure including the above quantum dot-polymer composite in at least one layer, and an electronic device including the same.

In an embodiment, the quantum dot comprises: a semiconductor nanocrystal core comprising indium (In) and phosphorus (P); and a semiconductor nanocrystal shell disposed on the semiconductor nanocrystal core, the semiconductor nanocrystal shell comprising zinc, selenium, and sulfur,

wherein the quantum dot has a maximum photoluminescence peak in a green wavelength region, and the ratio A is in an ultraviolet-visible (UV-Vis) absorption spectrum of the quantum dot₄₅₀/A_first(i.e., an absorption value at 450 nanometers (nm) relative to an absorption value of the first absorption peak) is greater than or equal to about 0.7, and a Valley Depth (VD) defined by the following equation is greater than or equal to about 0.4:

1-(Abs_valley/Abs_first)＝VD

wherein, Abs_firstIs the absorption value of the first absorption peak, Abs_valleyIs the absorption value at the lowest point of the trough adjacent to the first absorption peak, and

wherein the quantum dots do not include cadmium.

The semiconductor nanocrystal core may also include zinc.

In the quantum dots, the molar ratio of sulfur to selenium (S/Se) may be less than or equal to about 2.5: 1.

In the quantum dots, the molar ratio of sulfur to selenium (S/Se) may be less than or equal to about 1: 1.

In the quantum dots, the molar ratio of sulfur to selenium (S/Se) may be less than or equal to about 0.8: 1.

In the quantum dot, a molar ratio of zinc to indium (Zn/In) may be greater than or equal to about 10: 1.

In the quantum dots, the molar ratio of zinc to indium (Zn/In) may be less than or equal to about 50:1, less than or equal to about 49:1, less than or equal to about 48:1, less than or equal to about 47:1, or less than or equal to about 46: 1.

In the quantum dots, the molar ratio of zinc to indium is greater than or equal to about 26:1 and less than or equal to about 45: 1.

In the quantum dots, the molar ratio of the sum of selenium and sulfur to indium (S + Se)/In may be greater than or equal to about 10: 1.

In the quantum dots, the molar ratio of the sum of selenium and sulfur to indium (S + Se)/In may be less than or equal to about 40: 1.

The semiconductor nanocrystal shell may include a first shell layer including zinc and selenium and a second shell layer disposed on the first shell layer and including zinc and sulfur. The first shell layer may be located between the semiconductor nanocrystal core and the second shell layer.

The first shell layer may be disposed directly on the semiconductor nanocrystal core. The first shell may not include sulfur.

The second shell may not include selenium.

The second shell layer may be the outermost layer of the quantum dot (or semiconductor nanocrystal shell).

The green wavelength region may be greater than or equal to about 500 nm.

The green wavelength region may be less than or equal to about 560 nm.

The wavelength of the maximum photoluminescence peak may be greater than or equal to about 525nm and less than or equal to about 540 nm. The first absorption peak may be in a wavelength range greater than about 450nm and less than or equal to about the wavelength of the maximum photoluminescence peak.

The first absorption peak may be in a wavelength range of greater than or equal to about 455 nm.

The valley adjacent to the first absorption peak may be present in a wavelength range of greater than or equal to about 420nm, greater than or equal to about 425nm, greater than or equal to about 430nm, greater than or equal to about 440nm, greater than or equal to about 450nm, or greater than or equal to about 460 nm.

The valley (or the lowest point of the valley) may exist in a range of wavelengths less than or equal to about the first absorption peak.

The valley adjacent to the first absorption peak may be present in a wavelength range of less than or equal to about 490nm, less than or equal to about 485nm, less than or equal to about 480nm, less than or equal to about 475nm, or less than or equal to about 470 nm.

The valleys adjacent to the first absorption peak are present in a range of greater than or equal to about 420 nanometers and less than or equal to about 490 nanometers.

A ratio of an absorption value at 450nm to an absorption value at the first absorption peak in an ultraviolet-visible (UV-Vis) absorption spectrum of the quantum dot may be greater than or equal to about 0.75.

The Valley Depth (VD) may be greater than or equal to about 0.5.

The Valley Depth (VD) may be greater than or equal to about 0.52.

The quantum dots can constitute a population of quantum dots (i.e., present as a plurality of quantum dots) having an average size greater than or equal to about 4nm and less than or equal to about 8nm and a standard deviation of less than or equal to about 30% of the average size.

The quantum dots may have a maximum photoluminescence peak having a full width at half maximum of less than or equal to about 50nm (e.g., less than or equal to about 45nm or less than or equal to about 40 nm).

The quantum efficiency (quantum yield) of the quantum dots may be greater than or equal to about 80% or greater than or equal to about 84%.

In an embodiment, the composition includes the quantum dot(s), a dispersant, and an organic solvent described above. The dispersant may include a carboxylic acid group-containing binder polymer. The composition may also comprise (photo) polymerizable monomers comprising carbon-carbon double bonds and optionally (thermal or photo) polymerization initiators.

In an embodiment, the quantum dot-polymer composite includes a polymer matrix and the above-described quantum dot(s) (e.g., plurality) dispersed in the polymer matrix.

The polymer matrix may comprise a linear polymer, a cross-linked polymer, or a combination thereof.

The polymer matrix may include a carboxylic acid group-containing binder polymer.

The carboxylic acid group-containing binder polymer may include: a copolymer of a monomer mixture comprising a first monomer comprising a carboxylic acid group and a carbon-carbon double bond, a second monomer comprising a carbon-carbon double bond and a hydrophobic portion and not comprising a carboxylic acid group, and optionally a third monomer comprising a carbon-carbon double bond and a hydrophilic portion and not comprising a carboxylic acid group; a multiple aromatic ring-containing polymer comprising a backbone structure in which two aromatic rings are bonded to a quaternary carbon atom that is a constituent atom of another ring portion in the backbone of the backbone structure, the multiple aromatic ring-containing polymer comprising a carboxylic acid group (-COOH); or a combination of a copolymer and a polymer containing multiple aromatic rings.

The polymer matrix may include a crosslinked polymer, a linear polymer having carboxylic acid groups, or a combination thereof.

The polymer matrix can include a crosslinked polymer, and the crosslinked polymer includes a polymerization product of a monomer having at least two carbon-carbon double bonds, a polymerization product of the monomer with a polythiol compound comprising at least two thiol groups, or a combination thereof. The polymer matrix may include metal oxide fine particles dispersed in the polymer matrix.

The polymer matrix may also include a combination of monomers including carbon-carbon double bonds and a monothiol compound or a polymerizate of a polythiol compound, a metal oxide fine particle, or a combination thereof, the monothiol compound or the polythiol compound (e.g., at a terminus of a thiol compound) including at least one (or at least two) thiol groups.

The quantum dot-polymer composite may be in the form of a patterned film.

In an embodiment, a display device includes a light source and a light emitting element, wherein the light emitting element includes the aforementioned quantum dot-polymer composite, and the light source provides incident light to the light emitting element.

Based on BT2020, display devices can exhibit greater than or equal to about 80% color reproducibility. The incident light may have a luminescence peak wavelength of about 440 nanometers to about 460 nanometers.

In an embodiment, a light emitting element may include a sheet including a quantum dot-polymer composite.

In an embodiment, a light emitting element may include a stacked structure including a substrate and a light emitting layer disposed on the substrate, wherein the light emitting layer includes a pattern including a quantum dot-polymer composite.

The quantum dot-polymer composite pattern may include at least one repeating portion configured to emit light of a predetermined wavelength.

The quantum dot-polymer composite pattern may include a first portion configured to emit first light.

The quantum dot-polymer composite pattern may further include a second portion configured to emit second light having a center wavelength different from a center wavelength of the first light.

The quantum dot-polymer composite may include a blue light conversion of greater than or equal to about 29% after being heat treated at a temperature of about 180 ℃ for 30 minutes. The quantum dots of the embodiments may exhibit improved luminescent properties as well as enhanced (process) stability. Compositions comprising the above quantum dots may provide improved processability. Quantum dots may find use in various display devices and biomarkers (e.g., biosensors, bio-imaging, etc.), photodetectors, solar cells, hybrid compounds, and the like.

The quantum dots of the embodiments may exhibit enhanced blue light absorption, which may find their potential use in quantum dot-based photoluminescent color filters. The photoluminescent color filter may be used in display devices including various blue light sources (e.g., blue light emitting OLEDs, blue light emitting micro LEDs) and liquid crystal display devices including blue light sources.

Drawings

These and/or other aspects will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

fig. 1 is a view illustrating a ratio of a valley depth to an absorption intensity of an ultraviolet-visible absorption spectrum of a quantum dot according to an embodiment;

fig. 2 is an exploded view of a display device according to an embodiment;

fig. 3A is a cross-sectional view of a display device according to an embodiment;

fig. 3B is a cross-sectional view of a display device according to an embodiment;

fig. 4 is a cross-sectional view of a display device according to an embodiment; and

fig. 5 illustrates a process of fabricating a quantum dot-polymer composite pattern using a composition according to an embodiment.

Detailed Description

Advantages and features of the present disclosure and methods of accomplishing the same will become apparent with reference to the following example embodiments and the accompanying drawings. However, the embodiments should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like reference numerals refer to like elements throughout.

Unless otherwise defined, all terms (including technical and scientific terms) in the specification may be defined as commonly understood by one of ordinary skill in the art. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as including "at least one" unless the context clearly indicates otherwise. "at least one" is not to be construed as limiting "a" or "an". "or" means "and/or". As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

It will be further understood that the terms "comprises," "comprising," "includes" and/or "including," when used in this specification, specify the presence of stated features, regions, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components, and/or groups thereof.

It will be understood that when an element such as a layer, film, region or substrate is referred to as being "on" another element, it can be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly on" another element, there are no intervening elements present.

"about" or "approximately" as used herein includes the stated value and means within an acceptable range of deviation of the specified value, as determined by one of ordinary skill in the art, in view of the measurement in question and the error associated with measurement of the specified quantity (i.e., the limitations of the measurement system). For example, "about" may mean within one or more standard deviations, or within ± 10% or ± 5% of the stated value.

As used herein, the expression "does not include cadmium (or other heavy metal)" or "is substantially free of cadmium (or other heavy metal)" includes the case where the concentration of cadmium (or other heavy metal) may be less than or equal to about 100ppm, less than or equal to about 50ppm, less than or equal to about 10ppm, or virtually zero. In an embodiment, the amount of cadmium (or other heavy metal) is substantially absent, or if present, less than or equal to a detection limit or an impurity level as a given analytical tool (e.g., inductively coupled plasma atomic emission spectroscopy).

It will be understood that, although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings herein.

Exemplary embodiments are described herein with reference to cross-sectional illustrations that are schematic illustrations of idealized embodiments. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, the embodiments described herein should not be construed as limited to the particular shapes of regions as illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. For example, a region shown or described as flat may generally have rough and/or nonlinear features. Further, the acute angles shown may be rounded. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the precise shape of a region and are not intended to limit the scope of the present claims.

As used herein, unless a definition is otherwise provided, the term "substituted" refers to a compound or group (or moiety) in which at least one hydrogen atom is replaced with a substituent. Substituents may include C1 to C30 alkyl, C2 to C30 alkenyl, C2 to C30 alkynyl, C6 to C30 aryl, C7 to C30 alkylaryl, C1 to C30 alkoxy, C1 to C30 heteroalkyl, C3 to C40 heteroaryl, C3 to C30 heteroalkylaryl, C3 to C30 cycloalkyl, C3 to C15 cycloalkenyl, C6 to C30 cycloalkynyl, C2 to C30 heterocycloalkyl, halogen (-F, -Cl, -Br or-I), hydroxy (-OH), nitro (-NO), hydroxy (-NO₂) Cyano (-CN), amino (-NH-) or amino (-NRR 'where R and R' are the same or different and are independently hydrogen or C1 to C6 alkyl), azido (-N-O-H), or a salt thereof₃) Amidino (-C (═ NH)₂) Hydrazino (-NHNH)₂) Hydrazone group (═ N (NH)₂) Aldehyde (-)), aldehyde (-O) H), carbamoyl (-C (O) NH)₂) Thiol (-SH), ester (-C (═ O) OR where R is a C1 to C6 alkyl OR C6 to C12 aryl), carboxylic acid (-COOH) OR salts thereof (-C (═ O) OM where M is an organic OR inorganic cation), sulfonic acid (-SO) groups₃H) Or a salt thereof (-SO)₃M, wherein M is an organic cation or an inorganic cation), a phosphate group (-PO)₃H₂) Or a salt thereof (-PO)₃MH or-PO₃M₂Wherein M is an organic cation or an inorganic cation) or a combination thereof。

As used herein, unless a definition is otherwise provided, the term "hetero" refers to a compound or group that includes at least one (e.g., one to three) heteroatom (S), wherein the heteroatoms are each independently N, O, S, Si, P, or a combination thereof.

As used herein, unless a definition is otherwise provided, the term "alkylene" refers to a straight-chain (or branched) saturated aliphatic hydrocarbon group having a valence of at least two. Alkylene groups may be optionally (optionally) substituted with one or more substituents.

As used herein, unless a definition is otherwise provided, the term "arylene" refers to a functional group having a valence of at least two and formed by the removal of at least two hydrogen atoms from one or more rings of an aromatic hydrocarbon, wherein the hydrogen atoms may be removed from the same ring or different rings (preferably different rings), each of which may be aromatic or non-aromatic. The arylene group may be optionally substituted with one or more substituents.

As used herein, unless a definition is otherwise provided, the term "(meth) acrylate" refers to an acrylate and/or a methacrylate or a combination thereof. The (meth) acrylate may include a (C1 to C10 alkyl) acrylate, a (C1 to C10 alkyl) methacrylate, or a combination thereof.

As used herein, light conversion efficiency refers to the ratio of the amount of light emitted relative to the amount of light absorbed by the quantum dot-polymer composite, where the absorbed light is a fraction of the incident light (e.g., blue light) projected onto the quantum dot-polymer composite. The total amount (B) of incident light can be obtained by integrating a Photoluminescence (PL) spectrum of the incident light. The PL spectrum of the quantum dot-polymer composite film is measured to obtain the amount of light (a) in a green (or red) light wavelength region emitted from the quantum dot-polymer composite film and the amount of incident light (B') passing through the quantum dot-polymer composite film, and the light conversion efficiency is obtained by the following equation:

a/(B-B') × 100 ═ light conversion efficiency (%)

(B-B')/B × 100% ═ blue (blue) absorbance (%) of the film.

As used herein, unless a definition is otherwise provided, the term "dispersion" refers to a system in which the dispersed phase is a solid and the continuous phase comprises a liquid. For example, the term "dispersion" may refer to a colloidal dispersion in which the dispersed phase comprises particles having a size of at least about 1nm (e.g., at least about 2nm, at least about 3nm, or at least about 4nm) and less than or equal to about a few micrometers (μm) (e.g., 2 μm or less or 1 μm or less).

In the specification, the term "group" in group III, group II and the like means a group of the periodic table of elements.

As used herein, "group I" refers to group IA and IB, and may include Li, Na, K, Rb, and Cs, but is not limited thereto.

As used herein, "group II" refers to group IIA and group IIB, and examples of group II metals may include Cd, Zn, Hg, and Mg, but are not limited thereto.

As used herein, "group III" refers to group IIIA and group IIIB, and examples of the group III metal may include Al, In, Ga, and Tl, but are not limited thereto.

As used herein, "group IV" refers to group IVA and group IVB, and examples of group IV metals may include Si, Ge, and Sn, but are not limited thereto. As used herein, the term "metal" may include semimetals such as Si.

As used herein, "group V" refers to group VA and may include nitrogen, phosphorus, arsenic, antimony, and bismuth, but is not limited thereto.

As used herein, "group VI" refers to group VIA and may include, but is not limited to, sulfur, selenium, and tellurium.

As used herein, the term "first absorption peak wavelength" refers to a wavelength of a major exciton peak in (e.g., first appearing) the longest wavelength region of the UV-vis absorption spectrum of a quantum dot (i.e., a major exciton peak at (e.g., appearing) the lowest energy region in the UV-vis absorption spectrum).

Semiconductor nanocrystal particles (also known as quantum dots) are nano-sized crystalline materials. Semiconductor nanocrystal particles may have a large surface area per unit volume due to the relatively small size of the semiconductor nanocrystal particles, and may exhibit different characteristics from those of bulk materials having the same composition due to quantum confinement effects. The quantum dots may be excited by absorbing light from an excitation source and may emit energy corresponding to the energy band gap of the quantum dots.

Quantum dots have potential applicability in a variety of devices (e.g., electronic devices) due to their unique photoluminescence characteristics.

For use in photoluminescent color filters, quantum dots may have to have enhanced optical properties (e.g., luminance or absorption) and stability so that the quantum dots can maintain their luminescent properties even after exposure to the temperature and chemical conditions required for the patterning process.

Quantum dots having properties suitable for use in practical electronic devices may include cadmium and are commonly referred to in the art as cadmium-based quantum dots. However, cadmium is often involved in serious environmental/health impacts or concerns and is therefore a limited element for many commercial applications (e.g., consumer applications or products). As a kind of quantum dot, group III-V based nanocrystals (hereinafter, referred to as cadmium-free quantum dots) that do not include cadmium (e.g., substantially cadmium-free) have been extensively studied. However, many cadmium-free quantum dots have technical drawbacks or limitations compared to cadmium-based quantum dots. As noted in terms of stability (e.g., thermal stability), cadmium-free quantum dots can exhibit a dramatic decrease in luminescence or other optical properties when subjected to various manufacturing processes for fabricating electronic devices.

Quantum dots typically use blue light (e.g., having a wavelength of about 450 nm) as the excitation energy source in applications of electronic devices (e.g., electronic display devices). In contrast to cadmium-based quantum dots, which typically have a high level of blue light absorption, most currently known cadmium-free quantum dots (e.g., green light-emitting quantum dots) have blue light absorption values (e.g., absorption intensity or absorbance) that may not be sufficiently excited (e.g., having a wavelength of about 450 nm), which may result in a reduction in the brightness of the display device.

In cadmium-free quantum dots, the introduction of a core-shell structure has been demonstrated to enhance or improve the luminescent properties and thermal stability. For example, an InP-based core may be passivated with an increased thickness of ZnSe/ZnS shell and then applied in a quantum dot-polymer composite pattern. While it may be desirable to increase the thickness of the (e.g., ZnSe/ZnS) shell in order to achieve a suitable level of stability and luminescent properties, an increase in the thickness of the shell will also cause an increase in the weight (or relative weight) of each quantum dot. An increase in the weight of each quantum dot will then result in, for example, a decrease in the number density of quantum dots per given weight of quantum dot-polymer composite in the emissive layer of a display device, and thus will result in a decrease in the absorption of excitation light by the quantum dot-polymer composite.

If quantum dots are used in patterned quantum dot-polymer composite films, such as color filters, the reduction in excitation light absorption may be a direct cause of blue light leakage in display devices, which may adversely affect the color gamut (e.g., coverage under DCI standards) and lead to a reduction in luminous efficiency.

Quantum dot based display devices may exhibit improved color purity, brightness, and the like. For example, a liquid crystal display (hereinafter, referred to as an LCD) realizes colors by: the light, after passing through the liquid crystal, is polarized through an absorptive color filter. As a result, the LCD has problems of a narrow viewing angle and low light transmittance due to the absorption type color filter. On the other hand, the quantum dot may emit light having a theoretical quantum efficiency (QY) of about 100% and a high color purity, for example, a full width at half maximum (FWHM) of less than or equal to about 40nm, thereby achieving increased light emission efficiency and improved color reproducibility. Accordingly, the absorption type color filter may be replaced with a photo-luminescence type color filter including the quantum dots described herein to achieve a wider viewing angle and improved brightness.

Quantum dots can be dispersed in a host matrix (e.g., including a polymer and/or an inorganic material) to form a quantum dot-polymer composite (hereinafter, may also be simply referred to as a "composite"), which is then applied to the manufacture of electronic devices (e.g., display devices). It is commercially important to realize a quantum dot-polymer composite or a color filter including the quantum dot-polymer composite in a display device having high luminance, a wide viewing angle, and high color reproducibility, and thus has technical significance. However, the weight of quantum dots that can be included in composites for such applications may be limited for various process-related reasons. Accordingly, it would be desirable to develop quantum dots that can exhibit enhanced blue light absorption and improved brightness and thermal stability.

The quantum dots of the embodiments can exhibit enhanced luminescent (or optical) properties and stability (e.g., process stability or thermal stability) even in the absence of cadmium (e.g., even in the case of substantially cadmium-free quantum dots). As used herein, the term "quantum dot" may refer to a single particle or a plurality of particles.

In an embodiment, the quantum dots do not include cadmium. In an embodiment, the quantum dots are substantially cadmium-free. The quantum dots have a maximum photoluminescence peak in the green wavelength region. The green wavelength region may be greater than or equal to about 500nm, greater than or equal to about 510nm, greater than or equal to about 520nm, greater than or equal to about 525nm, greater than or equal to about 530nm, or greater than or equal to about 535nm and less than or equal to about 560nm, less than or equal to about 550nm, less than or equal to about 545nm, less than or equal to about 540nm, or less than or equal to about 539 nm. In an embodiment, the maximum photoluminescence peak may be present in any one of the aforementioned ranges, for example, in a range greater than or equal to about 530nm and less than or equal to about 540 nm.

The quantum dot includes a semiconductor nanocrystal core including indium (In) and phosphorus (P), and a semiconductor nanocrystal shell disposed on the semiconductor nanocrystal core and including zinc, selenium, and sulfur.

In an embodiment, the quantum dots may have a core-multishell structure. In an embodiment, the quantum dot may include: a core comprising indium phosphide (e.g., InP or InZnP); a first shell layer disposed on (or directly on) the core and comprising Zn and Se (e.g., ZnSe); and a second shell layer disposed on (or directly on) the first shell layer, having a composition different from that of the first shell layer, and including Zn and S (e.g., ZnS). In embodiments, the quantum dots do not include alkane monothiol compounds on their surface.

In embodiments, the semiconductor nanocrystal core may comprise InP or InZnP. The term "InZnP" may include alloys of indium phosphide and zinc phosphide as well as materials in which zinc is included in indium phosphide, for example, in doped or coated form.

The size of the core may be greater than or equal to about 1nm, greater than or equal to about 1.5nm, or greater than or equal to about 2 nm. In embodiments, the size of the core may be less than or equal to about 4nm, less than or equal to about 3nm, or less than or equal to about 2.7nm (e.g., less than or equal to about 2.5 nm).

As used herein, the term "size" may be the size of a single entity or the average size of a plurality of entities.

The inventors have found that in the case of quantum dots having an InP-based core and a shell comprising Zn, Se and S, it may be difficult to achieve an improved quality shell coating or to avoid an inhomogeneous shell coating, e.g. due to oxidation phenomena or differences between the crystal lattices of the core and shell materials before and/or during the shell passivation step. Since excitons are mainly generated in the core, an increase in surface oxidation of the InP core may also cause a significant decrease in light emission efficiency. In addition, defects on the surface of the quantum dot may cause a decrease in quantum efficiency because the uneven shell coating may not sufficiently separate the core of the quantum dot from the surface. According to the research of the present inventors, this may be a cause of the decrease in quantum efficiency after a color filter process step (e.g., a high temperature process step).

While an increase in shell thickness may partially address or minimize the problem of shell inhomogeneity, a thick shell of cadmium-free core-shell quantum dots may result in a significant increase in the weight of the quantum dots, which in turn results in a decrease in the number density of quantum dots per given weight of the composite in the quantum dot-polymer composite. In particular, in quantum dot based color filters, it is desirable to maximize the number density of quantum dots per given weight of composite. Therefore, in color filters based on cadmium-free quantum dots, the strategy of applying thick-shelled quantum dots may not be the optimal solution.

Therefore, it is desirable to develop such cadmium-free quantum dots: having a relatively thin shell to increase the number density of quantum dots per given weight of the composite while maintaining or improving the luminous efficiency and/or stability to a desired level.

The inventors have surprisingly demonstrated that the shape of the UV-Vis absorption spectrum (e.g., first absorption peak, valley adjacent thereto) and the ratio between the absorption intensity at 450nm and the absorption intensity at the first absorption peak can have a certain relationship to the degree of oxidation of the core and the uniform coating quality of the semiconductor nanocrystal core.

As shown in FIG. 1, in the ultraviolet-visible (UV-Vis) absorption spectrum of the quantum dot of the example, the absorption intensity (c) at 450nm (A)₄₅₀) And the absorption value (a) (A) at the first absorption peak (1)_first) Ratio of (i.e., A)₄₅₀/A_firstOr c/a) is greater than or equal to about 0.7, and the Valley Depth (VD) defined by the following equation is greater than or equal to about 0.4, e.g., greater than or equal to about 0.41, greater than or equal to about 0.42, greater than or equal to about 0.45, or greater than or equal to about 0.5:

1-(Abs_valley/Abs_first)＝VD

wherein, Abs_firstIs the absorbance value or absorbance (a), Abs at the first absorption peak (1)_valleyIs the absorption value or absorbance (b) at the lowest point of the trough adjacent to the first absorption peak (1).

The absorption value can be determined by absorption spectroscopy (i.e., UV-Vis absorption spectroscopy) using a commercially available spectrophotometer (e.g., Agilent Technology or Cary series spectrophotometer manufactured by Shimazdzu).

As used herein, the valley of the UV-Vis absorption spectrum refers to a portion (2) of the spectrum where the slope of the tangent line of the UV-Vis absorption spectrum curve changes from a negative value to a positive value as the wavelength increases. The valleys may be present near (adjacent to) the first absorption peak (1) (see fig. 1).

UV-Vis absorption spectroscopy involves the measurement of light in the visible and adjacent (near ultraviolet and near infrared) ranges. UV-Vis absorption spectroscopy is based on absorbance or absorption values. In spectroscopy, the absorbance or absorbance a can be defined as:

A_λ＝log₁₀(I₀/I)

where I is the light intensity at a given wavelength λ (transmitted light intensity) through the sample, I is₀Is the intensity of light (or incident light) before entering the sample. There are no actual units of absorbance or absorbance.

For green light emitting quantum dots having an InP-based core and a shell comprising Zn, Se, and S (e.g., ZnSe/ZnS shell), the present inventors have used an effective mass approximation method and obtained an absorption spectrum in InP/ZnSe/ZnS QDs, an energy level contributing to each of the first and second absorption peaks, and a wave function distribution corresponding to each energy level in the quantum dot structure. As a result, the present inventors have found that the intensity at the wavelength corresponding to the second absorption peak is the absorption intensity at 450nm, which is important for use in a quantum dot color filter, and the corresponding wave function relates not only to the InP core but also to a large part of the ZnSe shell and a part of the ZnS shell in a two-shell structure. Without wishing to be bound by any theory, such results indicate that in the UV-vis absorption spectrum, the second absorption peak may indicate the identity of the ZnSe shell and the ZnS shell. Further analysis of the absorption spectrum during shell formation can be performed using a gaussian function fit to mathematically separate the first and second absorption peaks in the absorption spectrum. Therefore, the present inventors have found that by adding the second shell layer ZnS, the second absorption peak may be blue-shifted with increasing intensity.

Without wishing to be bound by any theory, the spectroscopic results may also indicate that the formation of the two shells described above may lead to hybridization and an increase in energy level between the shells (e.g., ZnSe and ZnS) at an energy level associated with the second absorption peak. In the case of cadmium-free quantum dots with InP cores and shells comprising Zn, Se and S, the Valley Depth (VD) present in the UV-Vis absorption spectrum may represent the degree of hybridization between the shell components. In other words, from the spectral data, the increased valley depth in the UV-Vis absorption spectrum may indicate that the shell components (e.g., ZnSe and ZnS) are more uniformly coated and that the bonding area between them is also increased. Accordingly, the quantum dot of an embodiment may have the above VD value, thereby exhibiting improved quantum efficiency and enhanced process stability.

However, according to additional studies by the present inventors, increased VD values do not exclusively and completely correlate with all of the foregoing technical results. If the contribution of the ZnSe component is insufficient among the shell components (for example, two shell layers), the contribution of the ZnS component becomes relatively large, which may also cause an increase in VD value. In this case, even with a large VD value, the physical distance between the core and the final surface is insufficient for the quantum dot, and thus its corresponding surface state may have an adverse effect on the core, and the process stability related to the light emitting property of the quantum dot may be drastically reduced.

In the quantum dot of the embodiment, the ZnSe shell layer is sufficiently present (which can be confirmed by an absorption value (or intensity) at 450nm with respect to a first absorption value (or intensity) at the first absorption peak) for example, at a predetermined thickness or more, and thus the quantum dot may have the above-described ratio of the absorption value at 450nm with respect to the absorption value at the first absorption peak.

The quantum dot of an embodiment may have the above-described (composition) structure and the above-described VD value and the above-described ratio of the absorption (value or intensity) at 450nm to the absorption (value or intensity) at the first absorption peak. Accordingly, the quantum dot may exhibit improved optical properties (e.g., increased light emission efficiency and increased excitation absorption rate). The quantum dots may also exhibit relatively enhanced coating quality of the shell, which in turn may maximize the electronic shielding function of the shell. The quantum dots of the embodiments may be used to form quantum dot-polymer composite patterns.

In the quantum dots of the embodiments, the enhanced coating quality of the shell layer may enable the quantum dots to have a relatively reduced weight as well as improved stability (thermal stability) and enhanced optical properties, and thus the number density of quantum dots that may be included for a given weight of quantum dots in the quantum dot-polymer composite will also increase. Thus, the quantum dots of the embodiments may be used in a photoluminescent color filter.

Ratio A in UV-Vis absorption spectra of Quantum dots₄₅₀/A_first(i.e., the ratio of the absorption at 450nm to the absorption at the first absorption peak) can be greater than or equal to about 0.71, greater than or equal to about 0.72, greater than or equal to about 0.73, greater than or equal to about 0.74, greater than or equal to about 0.75, greater than or equal to about 0.76, greater than or equal to about 0.77, or greater than or equal to about 0.78. The valley depth may be greater than or equal to about 0.41, greater than or equal to about 0.45, greater than or equal to about 0.5, greater than or equal to about 0.52, or greater than or equal to about 0.53.

In the quantum dots of an embodiment, the molar ratio of sulfur to selenium (S/Se) may be less than or equal to about 2.5: 1. In the quantum dots of embodiments (e.g., green or red emitting QDs), the molar ratio of sulfur to selenium may be less than or equal to about 2.4:1, less than or equal to about 2.3:1, less than or equal to about 2.2:1, less than or equal to about 2.1:1, less than or equal to about 2.0:1, less than or equal to about 1.9:1, less than or equal to about 1.8:1, less than or equal to about 1.7:1, less than or equal to about 1.6:1, less than or equal to about 1.5:1, less than or equal to about 1.4:1, less than or equal to about 1.3:1, less than or equal to about 1.2:1, less than or equal to about 1.1:1, less than or equal to about 1:1, less than or equal to about 0.9:1, or less than or equal to about 0.8:1, less than or equal to about 0.7:1, less than or equal to about 0.65:1, or less than or equal to about 0.6: 1. In the quantum dots of the embodiments, the molar ratio of sulfur to selenium may be greater than or equal to about 0.05:1, greater than or equal to about 0.07:1, greater than or equal to about 0.1:1, greater than or equal to about 0.2:1, greater than or equal to about 0.3:1, greater than or equal to about 0.4:1, or greater than or equal to about 0.5: 1.

In embodiments of quantum dots, the molar ratio of zinc to indium may be greater than or equal to about 10:1, greater than or equal to about 15:1, greater than or equal to about 20:1, greater than or equal to about 25:1, greater than or equal to about 30:1, or greater than or equal to about 35: 1.

In embodiments of quantum dots, the molar ratio of zinc to indium may be less than or equal to about 50:1, less than or equal to about 49:1, less than or equal to about 48:1, less than or equal to about 47:1, less than or equal to about 46:1, less than or equal to about 45:1, less than or equal to about 44:1, less than or equal to about 43:1, less than or equal to about 42:1, less than or equal to about 41:1, less than or equal to about 40:1, less than or equal to about 39:1, less than or equal to about 38:1, or less than or equal to about 35: 1.

In embodiments of quantum dots, the molar ratio of the sum of sulfur and selenium relative to indium (Se + S)/In may be greater than or equal to about 10:1, greater than or equal to about 15:1, greater than or equal to about 19:1, greater than or equal to about 20:1, greater than or equal to about 21:1, greater than or equal to about 22:1, greater than or equal to about 23:1, greater than or equal to about 24:1, greater than or equal to about 25:1, greater than or equal to about 26:1, greater than or equal to about 27:1, greater than or equal to about 28:1, greater than or equal to about 29:1, or greater than or equal to about 30: 1. In embodiments of quantum dots, the molar ratio of the sum of sulfur and selenium relative to indium (Se + S)/In) may be less than or equal to about 40:1, less than or equal to about 39:1, less than or equal to about 38:1, less than or equal to about 37:1, less than or equal to about 36:1, less than or equal to about 35:1, less than or equal to about 34:1, less than or equal to about 33:1, or less than or equal to about 32: 1.

The semiconductor nanocrystal shell may include a first shell layer including zinc and selenium and a second shell layer disposed on the first shell layer and including zinc and sulfur. The first shell layer may be disposed directly on the core. The first shell layer may include ZnSe, ZnSeS, or a combination thereof. The first shell may not include sulfur.

In embodiments, the first shell layer can have a thickness of greater than or equal to about 3 Monolayers (ML), for example, greater than or equal to about 3.5ML, greater than or equal to about 3.6ML, greater than or equal to about 3.7ML, greater than or equal to about 3.8ML, greater than or equal to about 3.9ML, or greater than or equal to about 4 ML. In embodiments, the thickness of the first shell layer may be less than or equal to about 7ML, for example, less than or equal to about 6ML or less than or equal to about 5 ML.

In embodiments, the thickness of the first shell layer may be greater than or equal to about 0.9nm, greater than or equal to about 1nm, greater than or equal to about 1.1nm, greater than or equal to about 1.2nm, greater than or equal to about 1.3nm, greater than or equal to about 1.4nm, greater than or equal to about 1.5nm, or greater than or equal to about 1.6nm and less than or equal to about 2.5nm, less than or equal to about 2nm, less than or equal to about 1.9nm, less than or equal to about 1.8nm, less than or equal to about 1.75nm, less than or equal to about 1.7nm, less than or equal to about 1.4nm, less than or equal to about 1.3nm, or less than or equal to about 1.25 nm.

The second shell layer may include ZnS. The second shell may not include selenium. The second shell may be disposed directly on the first shell. The second shell layer may be an outermost layer of the quantum dot.

In embodiments, the thickness of the second shell layer may be less than or equal to about 0.7nm, e.g., less than or equal to about 0.7nm, less than or equal to about 0.65nm, less than or equal to about 0.64nm, less than or equal to about 0.63nm, less than or equal to about 0.62nm, less than or equal to about 0.61nm, less than or equal to about 0.6nm, less than or equal to about 0.59nm, less than or equal to about 0.58nm, less than or equal to about 0.57nm, less than or equal to about 0.56nm, less than or equal to about 0.55nm, less than or equal to about 0.54nm, or less than or equal to about 0.53 nm.

In embodiments, the thickness of the second shell layer may be greater than or equal to about 0.15nm, greater than or equal to about 0.16nm, greater than or equal to about 0.17nm, greater than or equal to about 0.18nm, greater than or equal to about 0.19nm, greater than or equal to about 0.2nm, greater than or equal to about 0.21nm, greater than or equal to about 0.22nm, greater than or equal to about 0.23nm, greater than or equal to about 0.24nm, greater than or equal to about 0.25nm, greater than or equal to about 0.26nm, or greater than or equal to about 0.27 nm.

In the UV-Vis absorption spectrum of the quantum dot, the first absorption peak may exist in a wavelength range greater than about 450nm and less than a maximum photoluminescence peak wavelength. The first absorption peak wavelength can be greater than or equal to about 455nm, for example, greater than or equal to about 460nm, greater than or equal to about 465nm, greater than or equal to about 470nm, greater than or equal to about 475nm, greater than or equal to about 480nm, greater than or equal to about 485nm, or greater than or equal to about 490 nm. The first absorption peak wavelength can be less than or equal to about 520nm, less than or equal to about 515nm, or less than or equal to about 510 nm.

The valley or its lowest point adjacent to the first absorption peak may exist in a wavelength range of greater than or equal to about 420nm (e.g., greater than or equal to about 425nm, greater than or equal to about 430nm, greater than or equal to about 435nm, greater than or equal to about 440nm, greater than or equal to about 445nm, greater than or equal to about 450nm, greater than or equal to about 455nm, or greater than or equal to about 460 nm). The trough or its lowest point adjacent to the first absorption peak may exist in a wavelength range of less than or equal to about 490nm (e.g., less than or equal to about 485nm, less than or equal to about 480nm, less than or equal to about 475nm, or less than or equal to about 470 nm).

In embodiments, the size (or average size) of the quantum dots may be greater than or equal to about 1nm, greater than or equal to about 2nm, greater than or equal to about 3nm, greater than or equal to about 4nm, or greater than or equal to about 5 nm. In embodiments, the size (or average size) of the quantum dots may be less than or equal to about 30nm, e.g., less than or equal to about 25nm, less than or equal to about 24nm, less than or equal to about 23nm, less than or equal to about 22nm, less than or equal to about 21nm, less than or equal to about 20nm, less than or equal to about 19nm, less than or equal to about 18nm, less than or equal to about 17nm, less than or equal to about 16nm, less than or equal to about 15nm, less than or equal to about 14nm, less than or equal to about 13nm, less than or equal to about 12nm, less than or equal to about 11nm, less than or equal to about 10nm, less than or equal to about 9nm, less than or equal to about 8nm, or less than or equal to about 7 nm.

The size of the quantum dots may be the diameter of the particles. In the case of non-spherical shaped particles, the size of the quantum dots may be calculated by converting the (e.g., two-dimensional) area of an electron microscopy image of the particle to a circle (e.g., equivalent circular area).

In an embodiment, the size (or average size) of the core may be appropriately selected according to the desired emission wavelength of the quantum dot. For example, the size (or average size) of the core may be greater than or equal to about 1nm, greater than or equal to about 1.5nm, or greater than or equal to about 2 nm. The size (or average size) of the core may be less than or equal to about 5nm, less than or equal to about 4nm, less than or equal to about 3nm, less than or equal to about 2.5nm, or less than or equal to about 2 nm.

In embodiments, the shell may have a thickness of greater than or equal to about 0.5nm, greater than or equal to about 0.6nm, greater than or equal to about 0.7nm, greater than or equal to about 0.8nm, or greater than or equal to about 0.9 nm. In embodiments, the shell may have a thickness of less than or equal to about 3nm, less than or equal to about 2.5nm, less than or equal to about 2nm, less than or equal to about 1.9nm, less than or equal to about 1.5nm, less than or equal to about 1.2nm, less than or equal to about 1nm, or less than or equal to about 0.9 nm.

The quantum dots may constitute a population of quantum dots exhibiting an improved size distribution. In embodiments, the population of quantum dots (or the plurality of quantum dots) can have a size distribution (standard deviation) of less than or equal to about 30%, less than or equal to about 20%, less than or equal to about 15%, less than or equal to about 14%, less than or equal to about 13%, less than or equal to about 12%, less than or equal to about 11%, or less than or equal to about 10%.

The shape of the quantum dot is not particularly limited, but may be, for example, a spherical, polyhedral, pyramidal, polypod or cubic shaped nanotube, nanowire, nanofiber, nanosheet or a combination thereof, but is not limited thereto.

The quantum dots can have a quantum efficiency of greater than or equal to about 70% (e.g., greater than or equal to about 72%, greater than or equal to about 75%, greater than or equal to about 80%, greater than or equal to about 85%, greater than or equal to about 86%, greater than or equal to about 87%, greater than or equal to about 88%, greater than or equal to about 89%, or greater than or equal to about 90%). The quantum dots may exhibit a maximum photoluminescence peak having a full width at half maximum of less than or equal to about 50nm or less than or equal to about 45 nm.

In embodiments, "quantum yield (or quantum efficiency)" is the ratio of photons emitted to photons absorbed, for example, by a nanostructure or group of nanostructures. In embodiments, the quantum efficiency may be determined by any method. For example, there may be two methods of measuring fluorescence quantum yield or efficiency: absolute and relative methods. The absolute method directly obtains the quantum yield by detecting the fluorescence intensity of all samples using an integrating sphere. The relative method compares the fluorescence intensity of the standard sample with the fluorescence intensity of the unknown sample to calculate the quantum yield of the unknown sample. QY can be easily determined by using commercially available equipment.

The quantum dots may include organic ligands, organic solvents, or a combination thereof on the surface of the quantum dots, which will be described below. An organic ligand, an organic solvent, or a combination thereof may be bound to the surface of the quantum dot.

In an embodiment, the quantum dots may be prepared by a method comprising: obtaining a semiconductor nanocrystal core; and forming a semiconductor nanocrystal shell, wherein the reaction conditions (temperature/time/amount of precursor) of the shell formation are controlled such that the resulting quantum dot can satisfy the aforementioned composition while exhibiting a UV-Vis spectrum having the aforementioned characteristics.

In an embodiment, the method may comprise the steps of:

obtaining a first mixture comprising a zinc-containing precursor (hereinafter, referred to as zinc precursor), an organic ligand, and an organic solvent;

optionally heating the first mixture;

injecting a semiconductor nanocrystal core comprising indium and phosphorus and a selenium-containing precursor into the (optionally heated) first mixture to obtain a second mixture;

heating the second mixture at the first reaction temperature and maintaining the first reaction temperature for at least about 40 minutes (e.g., at least about 50 minutes, at least about 60 minutes, at least about 70 minutes, or at least about 80 minutes) to obtain a third mixture comprising such particles: comprising a first shell layer comprising zinc and selenium formed on a semiconductor nanocrystal core; and

a sulfur-containing precursor (e.g., a stock solution including a sulfur-containing precursor) is injected into the third mixture at the first reaction temperature to form a second shell layer on the first shell layer.

In the method, the amount of selenium-containing precursor relative to the core in the second mixture and the amount of sulfur-containing precursor relative to the core in the third mixture (and optionally the reaction duration in each step) are controlled separately and independently of each other or each other such that the resulting quantum dot achieves the aforementioned shell composition and exhibits the aforementioned UV-Vis absorption spectrum.

The details of the quantum dots, semiconductor nanocrystal core, semiconductor nanocrystal shell (e.g., first shell layer and second shell layer) are the same as set forth above.

The zinc precursor is not particularly limited. In embodiments, the zinc precursor can include a Zn metal powder, an alkylated Zn compound (e.g., dimethyl zinc, diethyl zinc, or a combination thereof), a zinc alkoxide, a zinc carboxylate (e.g., zinc acetate), zinc carbonate, zinc nitrate, zinc perchlorate, zinc sulfate, zinc acetylacetonate, a zinc halide (e.g., zinc chloride, zinc bromide, zinc iodide, zinc fluoride, or a combination thereof), zinc cyanide, zinc hydroxide, zinc oxide, zinc peroxide, or a combination thereof.

Examples of zinc precursors may include, but are not limited to, dimethyl zinc, diethyl zinc, zinc acetate, zinc acetylacetonate, zinc iodide, zinc bromide, zinc chloride, zinc fluoride, zinc carbonate, zinc cyanide, zinc nitrate, zinc oxide, zinc peroxide, zinc perchlorate, zinc sulfate, and the like. The zinc-containing precursor may be used alone, or may be used in combination of two or more of the above-described precursor compounds.

The organic ligand may include RCOOH, RNH₂、R₂NH、R₃N、RSH、RH₂PO、R₂HPO、R₃PO、RH₂P、R₂HP、R₃P、ROH、RCOOR'、RPO(OH)₂、RHPOOH、R₂POOH (wherein R and R' are the same or different and are independently a substituted or unsubstituted C1 to C40 (or C3 to C24) aliphatic hydrocarbon group (e.g., alkyl, alkenyl, or alkynyl), a substituted or unsubstituted C6 to C40 aromatic hydrocarbon group (e.g., C6 to C20 aryl), a polymeric organic ligand, a polymerA body or a combination thereof.

The organic ligand may coordinate (e.g., bind) to the surface of the obtained nanocrystals, and may help to disperse the nanocrystals well in solution, and may also affect the light emission characteristics and/or electrical characteristics of the quantum dots.

Examples of organic ligands may include: methyl mercaptan, ethyl mercaptan, propyl mercaptan, butyl mercaptan, pentyl mercaptan, hexyl mercaptan, octyl mercaptan, dodecyl mercaptan, hexadecyl mercaptan, octadecyl mercaptan or benzyl mercaptan; methylamine, ethylamine, propylamine, butylamine, pentylamine, hexylamine, octylamine, dodecylamine, hexadecylamine, octadecylamine, dimethylamine, diethylamine, dipropylamine; formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, lauric acid, palmitic acid, stearic acid, oleic acid, or benzoic acid; phosphines such as substituted or unsubstituted methylphosphine (e.g., trimethylphosphine, methyldiphenylphosphine, etc.), substituted or unsubstituted ethylphosphine (e.g., triethylphosphine, ethyldiphenylphosphine, etc.), substituted or unsubstituted propylphosphine, substituted or unsubstituted butylphosphine, substituted or unsubstituted pentylphosphine, or substituted or unsubstituted octylphosphine (e.g., Trioctylphosphine (TOP)); phosphine oxides such as substituted or unsubstituted methylphosphine oxides (e.g., trimethylphosphine oxide, methyldiphenylphosphine oxide, etc.), substituted or unsubstituted ethylphosphine oxides (e.g., triethylphosphine oxide, ethyldiphenylphosphine oxide, etc.), substituted or unsubstituted propylphosphine oxides, substituted or unsubstituted butylphosphine oxides, or substituted or unsubstituted octylphosphine oxides (e.g., trioctylphosphine oxide (TOPO)); diphenylphosphine, triphenylphosphine, diphenylphosphine oxide or triphenylphosphine oxide; alkylphosphinic acids (e.g., C5 to C20 alkylphosphinic acids (e.g., hexylphosphinic acid, octylphosphinic acid, dodecylphosphinic acid, tetradecylphosphinic acid, hexadecylphosphinic acid, octadecylphosphinic acid, etc.)), alkylphosphinic acids (e.g., C5 to C20 alkylphosphinic acids); and the like, but are not limited thereto. The organic ligands may be used alone or as a mixture of at least two ligand compounds.

The organic solvent may be: primary C6 to C22 amines, such as hexadecylamine; secondary C6 to C22 amines, such as dioctylamine; c6 to C40 tertiary amines, such as trioctylamine; nitrogen-containing heterocyclic compounds such as pyridine; c6 to C40 aliphatic hydrocarbons (e.g., alkanes, alkenes, alkynes, etc.), such as hexadecane, octadecane, octadecene, or squalane; c6 to C30 aromatic hydrocarbons such as phenyl dodecane, phenyl tetradecane or phenyl hexadecane; phosphines substituted with C6 to C22 alkyl groups, such as trioctylphosphine; phosphine oxides substituted with C6 to C22 alkyl groups, such as trioctylphosphine oxide; c12 to C22 aromatic ethers such as phenyl ether or benzyl ether; or a combination thereof.

The type and amount of the organic solvent may be appropriately selected in consideration of the precursor and the organic ligand.

The first mixture can be heated to a predetermined temperature (e.g., greater than or equal to about 100 ℃, e.g., greater than or equal to about 120 ℃, greater than or equal to about 150 ℃, greater than or equal to about 200 ℃, greater than or equal to about 250 ℃, or greater than or equal to about 270 ℃ and less than or equal to about the first reaction temperature) under vacuum, an inert atmosphere, or a partial vacuum/inert atmosphere.

The details of the semiconductor nanocrystal core including indium and phosphorus are the same as set forth above. The core may be commercially available or may be prepared in any suitable manner. The preparation of the core is not particularly limited, but may be performed in any method of manufacturing an indium phosphide-based core. In an embodiment, the core may be synthesized in a thermal injection manner, wherein a solution comprising a metal-containing precursor (e.g., an indium-containing precursor) and optionally an organic ligand is heated at an elevated temperature (e.g., greater than or equal to about 200 ℃) and then a phosphorous-containing precursor is injected into the heated hot solution.

The selenium-containing precursor is not particularly limited, but may be desirably selected. In an embodiment, the selenium-containing precursor includes selenium-trioctylphosphine (Se-TOP), selenium-tributylphosphine (Se-TBP), selenium-triphenylphosphine (Se-TPP), tellurium-tributylphosphine (Te-TBP), or a combination thereof, but is not limited thereto.

The first reaction temperature may be suitably selected, and for example, may be greater than or equal to about 280 ℃, greater than or equal to about 290 ℃, greater than or equal to about 300 ℃, greater than or equal to about 310 ℃ or greater than or equal to about 315 ℃ and less than or equal to about 390 ℃, less than or equal to about 380 ℃, less than or equal to about 370 ℃, less than or equal to about 360 ℃, less than or equal to about 350 ℃, less than or equal to about 340 ℃ or less than or equal to about 330 ℃.

After or during heating of the second mixture to the first reaction temperature, the selenium-containing precursor may, for example, be injected at least once (e.g., at least two, at least three, at least four, or at least five times) or continuously, for example, at defined concentrations (such as less than 1M or less than 0.5M) at predetermined time intervals.

The reaction time (the reaction time to maintain the second mixture at the first reaction temperature) may be greater than or equal to about 40 minutes, such as greater than or equal to about 50 minutes, greater than or equal to about 60 minutes, greater than or equal to about 70 minutes, greater than or equal to about 80 minutes, or greater than or equal to about 90 minutes and less than or equal to about 4 hours, such as less than or equal to about 3 hours or less than or equal to about 2 hours, to form a third mixture comprising such particles: having a first shell layer comprising zinc and selenium disposed on a semiconductor nanocrystal core.

By reacting at the first reaction temperature for the foregoing period of time, a first shell layer comprising zinc and selenium and having a thickness of greater than or equal to about 1 Monolayer (ML) (e.g., greater than or equal to about 1.5ML, greater than or equal to about 1.7ML, or greater than or equal to about 3ML (or 1ML to 2.5ML or 1ML to 2ML)) can be formed. In this case, in the second mixture, the amount of the selenium-containing precursor with respect to indium may be controlled so that, during a predetermined reaction time, a first shell layer having a predetermined thickness (for example, 0.5nm or more, 0.7nm or more, 0.9nm or more, 1nm or more, or 1.2nm or more) may be formed.

In embodiments, the amount of selenium per 1 mole of indium may be greater than or equal to about 3 moles, greater than or equal to about 4 moles, greater than or equal to about 5 moles, greater than or equal to about 6 moles, greater than or equal to about 7 moles, greater than or equal to about 8 moles, greater than or equal to about 9 moles, or greater than or equal to about 10 moles, but is not limited thereto. In embodiments, the amount of selenium per 1 mole of indium may be less than or equal to about 20 moles, less than or equal to about 18 moles, less than or equal to about 15 moles, less than or equal to about 10 moles, or less than or equal to about 9 moles, but is not limited thereto.

The third mixture may not include a sulfur-containing precursor.

At the first reaction temperature, a stock solution including a sulfur-containing precursor is added to the third mixture to form a second shell layer on the first shell layer.

In an embodiment, the method of manufacturing the quantum dots does not include reducing the temperature of the third mixture to equal to or less than about 100 ℃, such as less than or equal to about 50 ℃ (e.g., 30 ℃ or less or room temperature). In other words, the method can include maintaining the temperature of the reaction mixture including the particle (the particle having the first shell on the core) at a temperature greater than or equal to 100 ℃ (e.g., greater than or equal to 50 ℃ or greater than or equal to 30 ℃).

The type of the sulfur-containing precursor is not particularly limited, but may be appropriately selected. The sulfur-containing precursor may include hexanethiol, octanethiol, decanethiol, dodecanethiol, hexadecanethiol, mercaptopropylsilane, thio-trioctylphosphine (S-TOP), thio-tributylphosphine (S-TBP), thio-triphenylphosphine (S-TPP), thio-trioctylamine (S-TOA), trimethylsilylthio, ammonium sulfide, sodium sulfide, or combinations thereof. The sulfur-containing precursor can be injected at least once (e.g., at least twice).

To facilitate hybridization with the ZnSe shell components, the injection of the sulfur-containing precursor can be performed intermittently or continuously in a controlled manner (at a concentration less than the concentration of the selenium-containing precursor when the first shell layer is formed, and for a time less than or equal to about 3 hours).

The duration for forming the second shell can be greater than or equal to about 5 minutes, greater than or equal to about 10 minutes, greater than or equal to about 15 minutes, greater than or equal to about 20 minutes, greater than or equal to about 25 minutes, greater than or equal to about 30 minutes, or greater than or equal to about 35 minutes and less than or equal to about 3 hours, less than or equal to about 2 hours, less than or equal to about 1 hour, less than or equal to about 50 minutes, less than or equal to about 45 minutes, or less than or equal to about 40 minutes.

In an embodiment, the amount of sulfur relative to 1 mole of indium in the third mixture may be controlled to obtain a desired shell composition (e.g., such that its thickness is less than or equal to about 0.7nm) in view of the reactivity of the precursors and the reaction temperature.

In embodiments, the amount of sulfur relative to 1 mole of indium in the third mixture can be greater than or equal to about 2 moles, greater than or equal to about 3 moles, greater than or equal to about 4 moles, greater than or equal to about 5 moles, greater than or equal to about 6 moles, greater than or equal to about 7 moles, greater than or equal to about 8 moles, greater than or equal to about 9 moles, or greater than or equal to about 10 moles. The amount of sulfur relative to 1 mole of indium in the third mixture can be less than or equal to about 45mol, less than or equal to about 40mol, less than or equal to about 35mol, less than or equal to about 30mol, less than or equal to about 25mol, less than or equal to about 20mol, less than or equal to about 19mol, less than or equal to about 18mol, less than or equal to about 17mol, less than or equal to about 16mol, less than or equal to about 15mol, less than or equal to about 14mol, less than or equal to about 13mol, less than or equal to about 12mol, less than or equal to about 11mol, less than or equal to about 10mol, less than or equal to about 9mol, less than or equal to about 8mol, less than or equal to about 7mol, less than or equal to about 6mol, or less than or equal to about 5 mol.

After the reaction, a non-solvent is added to the final reaction solution obtained to promote the precipitation of the organic ligand-coordinated quantum dots. The non-solvent may be a polar solvent that is miscible with the organic solvent used in the reaction and in which the nanocrystals are not dispersible. The non-solvent may be selected according to the organic solvent used in the reaction, and may be, for example, acetone, ethanol, butanol, isopropanol, ethylene glycol, water, Tetrahydrofuran (THF), dimethyl sulfoxide (DMSO), diethyl ether, formaldehyde, acetaldehyde, a solvent having a solubility parameter similar to that of the aforementioned solvents, or a combination thereof. The separation of the precipitated quantum dots may be performed by centrifugation, precipitation, chromatography or distillation. The isolated nanocrystals can be added to a washing solvent and washed, if desired. The washing solvent is not particularly limited, and may include a solvent having a solubility parameter similar to that of the organic ligand, and may include, for example, hexane, heptane, octane, chloroform, toluene, benzene, etc.

The quantum dots may be dispersed in a dispersion solvent. The quantum dots may form an organic solvent dispersion. The organic solvent dispersion may be free of water, may be free of water-miscible organic solvents, or a combination thereof. The dispersion solvent may be appropriately selected. The dispersion solvent may include (or consist of) the aforementioned organic solvent. The dispersion solvent may include a substituted or unsubstituted C1 to C40 aliphatic hydrocarbon, a substituted or unsubstituted C6 to C40 aromatic hydrocarbon, or a combination thereof (or consist of a substituted or unsubstituted C1 to C40 aliphatic hydrocarbon, a substituted or unsubstituted C6 to C40 aromatic hydrocarbon, or a combination thereof).

In an embodiment, the composition comprises: the aforementioned quantum dots (e.g., plurality); a dispersant (which may disperse the quantum dots and optionally may include a carboxylic acid group-containing (binder) polymer); and an organic solvent (and/or a liquid carrier). The composition may further comprise: polymerizable (e.g., photopolymerizable) monomers including carbon-carbon double bonds; and optionally an initiator (e.g., a photoinitiator or a thermal initiator). The composition may be photosensitive.

In the composition, the details of the quantum dots are the same as set forth above. The amount of the quantum dots in the composition may be appropriately selected depending on the types and amounts of other components in the composition and the end use thereof. In embodiments, the amount of quantum dots can be greater than or equal to about 1 weight percent (wt%), based on the total solids content of the composition, for example, greater than or equal to about 2 wt%, greater than or equal to about 3 wt%, greater than or equal to about 4 wt%, greater than or equal to about 5 wt%, greater than or equal to about 6 wt%, greater than or equal to about 7 wt%, greater than or equal to about 8 wt%, greater than or equal to about 9 wt%, greater than or equal to about 10 wt%, greater than or equal to about 15 wt%, greater than or equal to about 20 wt%, greater than or equal to about 25 wt%, greater than or equal to about 30 wt%, greater than or equal to about 35 wt%, or greater than or equal to about 40 wt%. The amount of quantum dots can be less than or equal to about 70 wt%, for example, less than or equal to about 65 wt%, less than or equal to about 60 wt%, less than or equal to about 55 wt%, or less than or equal to about 50 wt%, based on the total solids content of the composition. The weight percentages of the components may represent the amounts of the components in the composite as will be described below, based on the total solids content of the composition.

The compositions of the embodiments may be used to provide a pattern comprising quantum dot-polymer composites. In an embodiment, the composition may be a photoresist composition that may be suitable for a photolithography process. In other embodiments, the composition may be an ink composition that may be suitable for inkjet processes (e.g., droplet discharge methods such as inkjet printing). In embodiments, the composition may not include a conjugated polymer (other than the cardo binder described below). In an embodiment, the composition may include a conjugated (or conductive) polymer. As used herein, a conjugated polymer may be a polymer comprising conjugated double bonds, such as polyphenylene vinylene.

In the compositions of the examples, the dispersant is a compound capable of ensuring (e.g., improving) the dispersibility of the quantum dot. The dispersant may be a binder polymer. The binder polymer may include carboxylic acid groups (e.g., in the repeat units of the binder polymer). The binder polymer may be an (electrically) insulating polymer.

In an embodiment, the adhesive polymer may include: a copolymer of a monomer combination comprising a first monomer comprising a carboxylic acid group and a carbon-carbon double bond, a second monomer comprising a carbon-carbon double bond and a hydrophobic portion and not comprising a carboxylic acid group, and optionally a third monomer comprising a carbon-carbon double bond and a hydrophilic portion and not comprising a carboxylic acid group; a polymer containing a plurality of aromatic rings (for example, also referred to as a cardo binder) including a carboxylic acid group (-COOH) and including a skeleton structure in a main chain (for example, a skeleton structure included in a main chain), wherein the skeleton structure includes a cyclic group including a quaternary carbon atom and two aromatic rings bonded to the quaternary carbon atom; or a combination thereof.

The copolymer can include a first repeat unit derived from a first monomer, a second repeat unit derived from a second monomer, and optionally a third repeat unit derived from a third monomer. The types and amounts of the first monomer, the second monomer, and the third monomer may be appropriately selected. As the copolymer including the first monomer, the second monomer, and the optional third monomer, a conventional copolymer (an aqueous alkali-soluble binder polymer) used in a photoresist, which is commercially available, can be used.

In an embodiment, the adhesive polymer may include a polymer including a plurality of aromatic rings. Polymers containing multiple aromatic rings (also known as cardo binders) may be used, which may be commercially available.

The carboxylic acid group-containing binder can have an acid value of greater than or equal to about 50 milligrams of potassium hydroxide per gram (mg KOH/g). For example, the acid number of the carboxylic acid group-containing binder can be greater than or equal to about 60mg KOH/g, greater than or equal to about 70mg KOH/g, greater than or equal to about 80mg KOH/g, greater than or equal to about 90mg KOH/g, greater than or equal to about 100mg KOH/g, greater than or equal to about 110mg KOH/g, greater than or equal to about 120mg KOH/g, greater than or equal to about 125mg KOH/g, or greater than or equal to about 130mg KOH/g, but is not limited thereto. The acid number of the carboxylic acid group-containing binder can be less than or equal to about 250mg KOH/g, for example, less than or equal to about 240mg KOH/g, less than or equal to about 230mg KOH/g, less than or equal to about 220mg KOH/g, less than or equal to about 210mg KOH/g, less than or equal to about 200mg KOH/g, less than or equal to about 190mg KOH/g, less than or equal to about 180mg KOH/g, or less than or equal to about 160mg KOH/g, but is not limited thereto.

The weight average (or number average) molecular weight of the binder polymer (e.g., comprising carboxylic acid groups), such as carboxylic acid group-containing binder, can be greater than or equal to about 1000 grams per mole (g/mol), for example, greater than or equal to about 2000g/mol, greater than or equal to about 3000g/mol, or greater than or equal to about 5000 g/mol. The weight average (or number average) molecular weight of the binder polymer may be less than or equal to about 100000g/mol, for example, less than or equal to about 50000g/mol, less than or equal to about 25000g/mol, or less than or equal to about 10000 g/mol.

In the composition, the amount of dispersant (e.g., binder polymer) can be greater than or equal to about 0.5 wt%, for example, greater than or equal to about 1 wt%, greater than or equal to about 5 wt%, greater than or equal to about 10 wt%, greater than or equal to about 15 wt%, or greater than or equal to about 20 wt%, based on the total weight (or total solids content) of the composition. In embodiments, the amount of dispersant (e.g., binder polymer or carboxylic acid group-containing binder) can be less than or equal to about 50 wt%, less than or equal to about 40 wt%, less than or equal to about 35 wt%, less than or equal to about 33 wt%, or less than or equal to about 30 wt%, based on the total weight (or total solids content) of the composition.

In the composition according to an embodiment, the (photo) polymerizable monomer including at least one (e.g., at least two, at least three, or more) carbon-carbon double bond may include a (e.g., photopolymerizable) (meth) acrylate monomer. The (photo) polymerizable monomer may be a precursor of the insulating polymer. Examples of (photo) polymerizable monomers may include, but are not limited to, C1-C10 alkyl (meth) acrylates, ethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, 1, 4-butanediol di (meth) acrylate, 1, 6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol di (meth) acrylate, dipentaerythritol tri (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, bisphenol a epoxy (meth) acrylate, bisphenol a di (meth) acrylate, and mixtures thereof, Trimethylolpropane tri (meth) acrylate, ethylene glycol monomethyl ether (meth) acrylate, novolac epoxy (meth) acrylate, propylene glycol di (meth) acrylate, tris (meth) acryloyloxyethyl phosphate, or combinations thereof.

The amount of (photo) polymerizable monomer may be greater than or equal to about 0.5 wt%, for example, greater than or equal to about 1 wt% or greater than or equal to about 2 wt%, relative to the total weight (or total solids content) of the composition. The amount of (photo) polymerizable monomer can be less than or equal to about 50 wt%, e.g., less than or equal to about 40 wt%, less than or equal to about 30 wt%, less than or equal to about 28 wt%, less than or equal to about 25 wt%, less than or equal to about 23 wt%, less than or equal to about 20 wt%, less than or equal to about 18 wt%, less than or equal to about 17 wt%, less than or equal to about 16 wt%, or less than or equal to about 15 wt%, relative to the total weight (or total solids content) of the composition.

The (photo) initiator included in the composition may be used to polymerize the (photo) polymerizable monomer. The initiator may be a compound capable of generating a radical species under mild conditions (e.g., by light or heat) to facilitate initiation of a radical reaction (e.g., radical polymerization of a monomer). The initiator may be a thermal initiator or a photoinitiator. The initiator is not particularly limited and may be appropriately selected.

Examples of the thermal initiator may include Azobisisobutyronitrile (AIBN), Benzoyl Peroxide (BPO), and the like, but are not limited thereto.

The photoinitiator may be a compound capable of initiating free radical polymerization of the aforementioned photopolymerizable (e.g., acrylic) monomers, a thiol compound as will be described below, or a combination thereof. The photoinitiator is not particularly limited. The photoinitiator may include a triazine compound, an acetophenone compound, a benzophenone compound, a thioxanthone compound, a benzoin compound, an oxime compound, an aminoketone compound, a phosphine or phosphine oxide compound, a carbazole compound, a diketone compound, a sulfonium borate compound, a diazo compound, a diimidazole compound, an azo compound, a biimidazole compound, or a combination thereof.

In the compositions of the examples, the amount of initiator may be adjusted according to the type and amount of (photo) polymerizable monomer as used. In embodiments, the amount of initiator may be greater than or equal to about 0.01 wt%, or greater than or equal to about 1 wt% and less than or equal to about 10 wt%, less than or equal to about 9 wt%, less than or equal to about 8 wt%, less than or equal to about 7 wt%, less than or equal to about 6 wt%, or less than or equal to about 5 wt%, based on the total weight (or total solids content) of the composition, but is not limited thereto.

The (photosensitive) composition may further include a thiol compound (e.g., a monothiol compound or a polythiol compound having two or more thiol groups), metal oxide fine particles, or a combination thereof.

When a plurality of metal oxide fine particles are present in the polymer matrix, the metal oxide fine particles may include TiO₂、SiO₂、BaTiO₃、Ba₂TiO₄ZnO, or combinations thereof. The particle size (or average particle size, hereinafter referred to as particle size) of the metal oxide fine particles is not particularly limited, but may be appropriately selected. The particle size of the metal oxide fine particles may be greater than or equal to about 100nm, greater than or equal to about 150nm, or greater than or equal to about 200nm and less than or equal to about 1000nm, less than or equal to about 900nm, or less than or equal to about 800 nm. The metal oxide fine particles may be non-luminescent.

The amount of metal oxide fine particles can be less than or equal to about 50 wt%, less than or equal to about 40 wt%, less than or equal to about 30 wt%, less than or equal to about 25 wt%, less than or equal to about 20 wt%, less than or equal to about 15 wt%, less than or equal to about 10 wt%, or less than or equal to about 5 wt%, based on the total weight (or total solids content) of the composition. The amount of metal oxide fine particles can be greater than or equal to about 1 wt%, greater than or equal to about 5 wt%, or greater than or equal to about 10 wt%, based on the total weight (or total solids content) of the composition.

The polythiol compound may include a compound represented by chemical formula 1:

chemical formula 1

Wherein the content of the first and second substances,

R¹is hydrogen; substituted or unsubstituted C1 to C30 straight or branched chain alkyl; a substituted or unsubstituted C6 to C30 aryl group; substituted or unsubstituted C3 to C30 heteroaryl; substituted or unsubstituted C3 to C30 cycloalkyl; substituted orUnsubstituted C3 to C30 heterocycloalkyl; c1 to C10 alkoxy; a hydroxyl group; -NH₂(ii) a A substituted or unsubstituted C1 to C30 amine group, wherein-NRR 'wherein R and R' are independently hydrogen or a C1 to C30 linear or branched alkyl group, but not both; an isocyanate group; halogen; -ROR ', wherein R is a substituted or unsubstituted C1 to C20 alkylene group and R' is hydrogen or a C1 to C20 linear or branched alkyl group; an acid halide, wherein-RC (═ O) X, wherein R is a substituted or unsubstituted alkylene group, and X is a halogen; -C (═ O) OR ', wherein R' is hydrogen OR a C1 to C20 linear OR branched alkyl group; -CN; -C (═ O) NRR ', wherein R and R' are independently hydrogen or C1 to C20 linear or branched alkyl; -C (═ O) ONRR ', wherein R and R' are independently hydrogen or C1 to C20 linear or branched alkyl; or a combination thereof,

L₁is a carbon atom, a substituted or unsubstituted C1 to C30 alkylene group, a substituted or unsubstituted C1 to C30 alkylene group in which the methylene group is substituted with a sulfonyl moiety, a carbonyl moiety, an ether moiety, a thioether moiety, a sulfoxide moiety, an ester moiety, an amide moiety comprising hydrogen or a C1 to C10 alkyl group, or a combination thereof, or an unsubstituted C1 to C30 alkylene group, a substituted or unsubstituted C3 to C30 cycloalkylene group, a substituted or unsubstituted C6 to C30 arylene group, a substituted or unsubstituted C3 to C30 heteroarylene group, or a substituted or unsubstituted C3 to C30 heterocycloalkylene group,

Y₁is a single bond; substituted or unsubstituted C1 to C30 alkylene; substituted or unsubstituted C2 to C30 alkenylene; or a substituted C1 to C30 alkylene or substituted C2 to C30 alkenylene group or an unsubstituted C1 to C30 alkylene group or an unsubstituted C2 to C30 alkenylene group in which a methylene group is substituted with a sulfonyl moiety, a carbonyl moiety, an ether moiety, a thioether moiety, a sulfoxide moiety, an ester moiety, an amide moiety including hydrogen or a C1 to C10 linear or branched alkyl group, an imide moiety including hydrogen or a C1 to C10 linear or branched alkyl group, or a combination thereof,

m is an integer of 1 or more,

k1 is 0 or an integer of 1 or more, k2 is an integer of 1 or more, and

the sum of m and k2 is an integer of 3 or more,

front lifting barThe member being m not exceeding Y₁And the sum of k1 and k2 does not exceed L₁The valence of (3).

The polythiol compound can include a dithiol compound, a trithiol compound, a tetrathiol compound, or a combination thereof. For example, the polythiol compound can include glycol di-3-mercaptopropionate (e.g., ethylene glycol di-3-mercaptopropionate), glycol dimercaptoacetate (e.g., ethylene glycol dimercaptoacetate), trimethylolpropane tris (3-mercaptopropionate), pentaerythritol tetrakis (2-mercaptoacetate), 1, 6-hexanedithiol, 1, 3-propanedithiol, 1, 2-ethanedithiol, polyethylene glycol dithiol comprising 1 to 10 ethylene glycol repeating units, or a combination thereof.

The amount of thiol compound can be less than or equal to about 50 wt%, less than or equal to about 40 wt%, less than or equal to about 30 wt%, less than or equal to about 20 wt%, less than or equal to about 15 wt%, or less than or equal to about 10 wt%, based on the total weight (or total solids content) of the composition. The amount of thiol compound can be greater than or equal to about 1 wt%, for example, greater than or equal to about 5 wt%, greater than or equal to about 10 wt%, greater than or equal to about 15 wt%, or greater than or equal to about 20 wt%, based on the total weight (or total solids content) of the composition.

The composition may further include an organic solvent (or liquid carrier) (hereinafter, simply referred to as "solvent"). The solvent is not particularly limited. The type and amount of the solvent may be appropriately selected by taking into consideration the aforementioned main components, i.e., the quantum dots, the dispersant, the (photo) polymerizable monomer, (photo) initiator, and, if used, the thiol compound, and the type and amount of the additives to be described below. In addition to the desired amount of solids content (non-volatile components), the composition may contain a residual amount of solvent.

The solvent may be appropriately selected by taking into consideration other components in the composition (e.g., a binder, a (photo) polymerizable monomer, (photo) initiator, and other additives), affinity for an alkali developing solution, boiling point, and the like. Non-limiting examples of solvents may include, but are not limited to: 3-ethoxypropionic acid ethyl ester; ethylene glycol series, such as ethylene glycol, diethylene glycol or polyethylene glycol; glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, ethylene glycol diethyl ether or diethylene glycol dimethyl ether; glycol ether acetates such as ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monoethyl ether acetate or diethylene glycol monobutyl ether acetate; the propylene glycol series, such as propylene glycol; propylene glycol ethers such as propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, propylene glycol dimethyl ether, dipropylene glycol dimethyl ether, propylene glycol diethyl ether or dipropylene glycol diethyl ether; propylene glycol ether acetates such as propylene glycol monomethyl ether acetate or dipropylene glycol monoethyl ether acetate; amides such as N-methylpyrrolidone, dimethylformamide or dimethylacetamide; ketones such as Methyl Ethyl Ketone (MEK), methyl isobutyl ketone (MIBK), or cyclohexanone; petroleum products such as toluene, xylene or solvent naphtha; esters such as ethyl acetate, propyl acetate, butyl acetate, cyclohexyl acetate, or ethyl lactate; ethers such as diethyl ether, dipropyl ether or dibutyl ether; chloroform; c1 to C40 aliphatic hydrocarbons (e.g., alkanes, alkenes, or alkynes); halogen (e.g., chlorine) -substituted C1 to C40 aliphatic hydrocarbons (e.g., dichloroethane, chloroform, etc.); c6 to C40 aromatic hydrocarbons (e.g., toluene, xylene, etc.); halogen (e.g., chlorine) -substituted C6 to C40 aromatic hydrocarbons; or a combination thereof.

In addition to the aforementioned components, the composition may further include various additives such as a light diffusing agent, a leveling agent, or a coupling agent. The amount of the additive is not particularly limited and may be selected within an appropriate range, wherein the additive does not adversely affect the preparation of the composition, the preparation of the quantum dot-polymer composite, and optionally the patterning of the composite. The type and examples of the aforementioned additives may include any suitable compounds having the desired functions, without particular limitation.

If present, the amount of the additive can be greater than or equal to about 0.1 wt%, for example, greater than or equal to about 0.5 wt%, greater than or equal to about 1 wt%, greater than or equal to about 2 wt%, or greater than or equal to about 5 wt%, based on the total weight of the composition (or the total solids content of the composition), but is not limited thereto. If present, the amount of additive may be less than or equal to about 20 wt%, for example, less than or equal to about 19 wt%, less than or equal to about 18 wt%, less than or equal to about 17 wt%, less than or equal to about 16 wt%, or less than or equal to about 15 wt%, but is not limited thereto.

The composition according to the examples may be prepared by a process comprising the steps of: preparing a quantum dot dispersion comprising the aforementioned quantum dots, a dispersant and a solvent; and mixing the quantum dot dispersion with an initiator, a polymerizable monomer (e.g., an acrylic monomer), an optional thiol compound, an optional metal oxide fine particle, and an optional additive. Each component may be mixed sequentially or simultaneously, but the mixing order is not particularly limited.

Reference may be made to US-2017-.

The composition may provide a quantum dot-polymer composite or a pattern of quantum dot-polymer composites via polymerization (e.g., photopolymerization).

In an embodiment, the quantum dot-polymer composite may include a polymer matrix and the aforementioned quantum dots dispersed in the polymer matrix.

The polymer matrix may include a crosslinked polymer, a linear polymer having carboxylic acid groups, or a combination thereof. The linear polymer having carboxylic acid groups can act as a dispersant (e.g., a binder polymer including carboxylic acid groups), and the crosslinked polymer can include a polymerization product of a polymerizable monomer including (at least one, e.g., at least two, at least three, at least four, or at least five) carbon-carbon double bonds (e.g., an insulating polymer), a polymerization product of a polymerizable monomer and a polythiol compound including at least two thiol groups (e.g., at a terminus of the polythiol compound), or a combination thereof. The quantum dot-polymer composite may also include metal oxide fine particles dispersed in a polymer matrix.

In an embodiment, the polymer matrix may include a cross-linked polymer and a dispersant (e.g., a (carboxyl-containing) binder polymer). The polymer matrix may not include a conjugated polymer (other than the cardo binder). The crosslinked polymer may include a thiol ene (thiolane) resin, a crosslinked poly (meth) acrylate, or a combination thereof. In embodiments, the crosslinked polymer can be the polymerization product of a polymerizable monomer and optionally a polythiol compound.

The details of the quantum dots, the dispersant (or binder polymer), the polymerizable monomer, and the polythiol compound are the same as described above.

The amount of the quantum dots (or the amount of the metal oxide fine particles) in the composite may correspond to the aforementioned amount range, based on the total solid content of the composite. In the composite, the amount of polymer matrix can be greater than or equal to about 3 wt%, greater than or equal to about 5 wt%, greater than or equal to about 10 wt%, greater than or equal to about 15 wt%, greater than or equal to about 20 wt%, or any combination thereof, based on the total weight of the composite. In the composite, the amount of polymer matrix can be less than or equal to about 97 wt%, less than or equal to about 95 wt%, less than or equal to about 90 wt%, less than or equal to about 80 wt%, less than or equal to about 70 wt%, or any combination thereof, based on the total weight of the composite.

The thickness of the quantum dot-polymer composite film (or quantum dot-polymer composite pattern to be described below) can be, for example, less than or equal to about 30 micrometers (μm), e.g., less than or equal to about 25 μm, less than or equal to about 20 μm, less than or equal to about 15 μm, less than or equal to about 10 μm, less than or equal to about 8 μm, less than or equal to about 7 μm, and greater than or equal to about 2 μm, e.g., greater than or equal to about 3 μm, greater than or equal to about 3.5 μm, greater than or equal to about 4 μm, greater than or equal to about 5 μm, or greater than or equal to about 6 μm.

In an embodiment, the patterned film includes a repeating portion comprising a first portion that emits a first light, wherein the first portion includes a quantum dot-polymer composite.

The repeating portion may include a second portion emitting second light having a maximum photoluminescence peak wavelength different from a maximum photoluminescence peak wavelength of the first light. The second part may comprise a quantum dot-polymer composite. The second portion of the quantum dot-polymer composite may include a second quantum dot configured to emit a second light. The second quantum dot may include the aforementioned quantum dot. The first light or the second light may be red light having a maximum photoluminescence peak wavelength existing between about 600nm and about 650nm (e.g., about 620nm to about 650nm) or green light having a maximum photoluminescence peak wavelength existing between about 500nm and about 550nm (e.g., about 510nm to about 540 nm). The patterned film may further include a third portion that emits or passes third light (e.g., blue light) different from the first and second light. The third light may have a maximum (e.g., photoluminescence) peak wavelength ranging from 380nm to 480 nm.

In an embodiment, a display device includes a light source and a photoluminescent element including a substrate and an emissive layer disposed on the substrate, the emissive layer including a quantum dot-polymer composite film (or patterned film). The light source is configured to provide incident light to the photoluminescent element. The peak wavelength of the luminescence of the incident light may be greater than or equal to about 440nm, for example, greater than or equal to about 450nm and less than or equal to about 500nm, for example, less than or equal to about 480nm, less than or equal to about 470nm, or less than or equal to about 460 nm.

In an embodiment, the photoluminescent element may comprise a quantum dot-polymer composite sheet. The display device may further include a liquid crystal panel, and the quantum dot-polymer composite sheet may be disposed between the light source and the liquid crystal panel. Fig. 2 shows an exploded view of the display device. Referring to fig. 2, the display device may have a structure in which a reflector, a Light Guide Panel (LGP), and a Blue LED light source (Blue-LED), a quantum dot-polymer composite sheet (QD sheet), and various optical films such as a prism, a Dual Brightness Enhancement Film (DBEF), and the like are stacked and a Liquid Crystal (LC) panel is disposed thereon.

In an embodiment of a display device, the emissive layer comprises a quantum dot-polymer composite pattern of an embodiment. The quantum dot-polymer composite pattern may include at least one repeating portion configured to emit light of a predetermined wavelength. The quantum dot-polymer composite pattern may include a first repeating portion that may emit a first light, a second repeating portion that may emit a second light, or a combination thereof. The preparation of the quantum dot-polymer composite pattern may be performed by photolithography or inkjet.

The first light and the second light have different maximum photoluminescence peak wavelengths in the photoluminescence spectrum. In an embodiment, the first light may be red light (R) having a maximum photoluminescence peak wavelength of about 600nm to about 650nm (e.g., about 620nm to about 650nm), and the second light may be green light (G) having a maximum photoluminescence peak wavelength of about 500nm to about 550nm (e.g., about 510nm to about 550nm), or vice versa (i.e., the first light may be green light and the second light may be red light).

The quantum dot-polymer composite pattern may also include a third portion that may emit and/or transmit third light (e.g., blue light) that is different from the first light and the second light. The maximum (e.g., photoluminescence) peak wavelength of the third light may be greater than or equal to about 380nm and less than or equal to about 480 nm.

An optical element (e.g., an excitation light blocking layer or a first filter to be described below) for blocking (e.g., reflecting or absorbing) excitation light (e.g., blue light and/or green light) may be provided on the front surface (light emitting surface) of the first portion, the second portion, or a combination thereof.

In the display device, the light source may include a plurality of light emitting cells corresponding to the first and second portions, respectively, and the light emitting cells may include first and second electrodes facing each other and an electroluminescent layer disposed between the first and second electrodes. The electroluminescent layer may comprise an organic light emitting material. For example, each light emitting unit of the light source may include an electroluminescent device (e.g., an Organic Light Emitting Diode (OLED)) configured to emit light of a predetermined wavelength (e.g., blue light, green light, or a combination thereof). The structure and material of the electroluminescent device, such as an Organic Light Emitting Diode (OLED), may be appropriately selected without particular limitation. The light source comprises an Organic Light Emitting Diode (OLED) emitting blue light (and optionally green light).

Fig. 3A and 3B are schematic cross-sectional views of a display device according to an embodiment. Referring to fig. 3A and 3B, the light source includes an organic light emitting diode OLED emitting blue light. The blue light of the organic light emitting diode OLED may be based on phosphorescent emission, fluorescent emission or a combination of both. The organic light emitting diode OLED may include: pixel electrodes (at least two, e.g., three or more) 90a, 90b, 90c formed on the substrate 100;

pixel defining layers

150a, 150b formed between the

adjacent pixel electrodes

90a, 90b, 90 c; organic

light emitting layers

140a, 140b, 140c formed on the

pixel electrodes

90a, 90b, 90 c; and a common electrode 130 formed on the

organic emission layers

140a, 140b, 140 c.

A thin film transistor and a substrate may be disposed under the organic light emitting diode OLED.

The pixel regions of the organic light emitting diode OLED may be disposed to correspond to a first portion, a second portion, and a third portion, respectively, which will be described in detail below.

A stacked structure including a pattern of quantum dot-polymer composites (e.g., a portion (R) including red quantum dots and a portion (G) including green quantum dots) and a substrate may be disposed on the light source. These portions are configured such that excitation light (e.g., blue light) emitted from the light source enters therein, and can emit red light and green light, respectively. The excitation light (e.g., blue or green light) emitted from the light source may pass through the third portion.

Light (e.g., blue and/or green light) emitted from the light source may enter the second and

first portions

21 and 11 of the quantum dot-polymer composite pattern 170 to emit (e.g., converted) red and green light R and G, respectively. The excitation light (B) emitted from the light source passes through the third portion 31 or is transmitted from the third portion 31. An optical element 160 may be disposed over the second portion that emits red light, the first portion that emits green light, or a combination thereof. The optical element may be an excitation light (blue) cut-off layer that cuts off (e.g., reflects or absorbs) blue light and optionally green light, or a first filter layer 310 (see fig. 4). An excitation light (e.g., blue and/or optionally green) cut-off layer 160 may be disposed on the upper substrate 240. The excitation light cut-off layer 160 may be disposed between the upper substrate 240 and the quantum dot-polymer composite pattern and over the first and

second portions

11 and 21. The details of the excitation light (blue) cut-off layer are the same as set forth below for first filter layer 310.

The display device may be obtained by separately manufacturing the stacked structure and the LED or OLED (e.g., emitting blue light) and then assembling them. Alternatively, a display device may be obtained by forming the quantum dot-polymer composite pattern of the embodiment on an LED or an OLED.

The substrate may be a substrate comprising an insulating material. The substrate may include: glass; various polymers such as polyesters (e.g., polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polymethacrylates, or polyacrylates); a polycarbonate; polysiloxanes (e.g., Polydimethylsiloxane (PDMS)); inorganic materials, such as Al₂O₃Or ZnO; or a combination thereof, but is not limited thereto. The thickness of the substrate may be appropriately selected in consideration of the substrate material, but the thickness of the substrate is not particularly limited. The substrate may have flexibility. The transmittance of the substrate may be greater than or equal to about 50%, greater than or equal to about 60%, greater than or equal to about 70%, greater than or equal to about 80%, or greater than or equal to about 90% for light emitted from the quantum dots.

A wiring layer including a thin film transistor and the like is formed over a substrate. The wiring layer may further include a gate line, a sustain voltage line, a gate insulating layer, a data line, a source electrode, a drain electrode, a semiconductor, a protective layer, and the like. The detailed structure of the routing layer may be determined according to embodiments. The gate line and the sustain voltage line are electrically separated from each other, and the data line is insulated from and crosses the gate line and the sustain voltage line. The gate electrode, the source electrode, and the drain electrode form a control terminal, an input terminal, and an output terminal of the thin film transistor, respectively. The drain electrode is electrically connected to a pixel electrode which will be described below.

The pixel electrode may serve as an anode of the display device. The pixel electrode may be formed of a transparent conductive material such as Indium Tin Oxide (ITO) or Indium Zinc Oxide (IZO). The pixel electrode may be formed of a material having a light blocking property, such as gold (Au), platinum (Pt), nickel (Ni), tungsten (W), chromium (Cr), molybdenum (Mo), iron (Fe), cobalt (Co), copper (Cu), palladium (Pd), or titanium (Ti). The pixel electrode may have a two-layer structure in which a transparent conductive material and a material having a light blocking property are sequentially stacked.

Between two adjacent pixel electrodes, a Pixel Defining Layer (PDL) may overlap an end of the pixel electrode to divide the pixel electrode into pixel units. The pixel defining layer is an insulating layer that may electrically block at least two pixel electrodes.

The pixel defining layer covers a portion of an upper surface of the pixel electrode, and a remaining region of the pixel electrode not covered by the pixel defining layer may provide an opening. An organic emission layer, which will be described below, may be formed in the region defined by the opening.

The organic emission layer defines each pixel region by the pixel electrode and the pixel defining layer. In other words, one pixel region may be defined as a region where one organic emission unit layer is formed, the organic emission unit layer being in contact with one pixel electrode divided by the pixel defining layer.

For example, in the display device according to the embodiment, the organic emission layer may be defined as a first pixel region, a second pixel region, and a third pixel region, and each pixel region is spaced apart from each other with a predetermined interval left by the pixel defining layer.

In an embodiment of the display device, the organic emission layer may emit third light belonging to a visible light region or to a UV region. That is, each of the first to third pixel regions of the organic emission layer may emit the third light. In an embodiment, the third light may be light having the highest energy in a visible light region, and may be, for example, blue light and/or green light. When all the pixel regions of the organic emission layer are designed to emit the same light, each pixel region of the organic emission layer may be entirely formed of the same or similar material, or formed of a material that may exhibit the same or similar properties. Accordingly, the process difficulty of forming the organic emission layer can be significantly reduced, and thus the display device can be easily applied to a large-size/large-area process. However, the organic emission layer according to the embodiment is not necessarily limited thereto, and the organic emission layer may be designed to emit at least two different lights.

The organic emission layer includes an organic emission unit layer in each pixel region, and each organic emission unit layer may further include an auxiliary layer (e.g., a Hole Injection Layer (HIL), a Hole Transport Layer (HTL), an Electron Transport Layer (ETL), etc.) in addition to the emission layer.

The common electrode may serve as a cathode of the display device. The common electrode may be formed of a transparent conductive material such as Indium Tin Oxide (ITO) or Indium Zinc Oxide (IZO). The common electrode may be formed on the organic emission layer and may be integrated with the organic emission layer.

A planarization layer or a passivation layer may be formed on the common electrode. The planarization layer may include an insulating material (e.g., transparent) for ensuring electrical insulation from the common electrode.

In an embodiment, the display device may further include a lower substrate, a polarizer disposed under the lower substrate, and a liquid crystal layer disposed between the stacked structure and the lower substrate, and in the stacked structure, the organic emission layer may be disposed to face the liquid crystal layer. The display device may further include a polarizer between the liquid crystal layer and the organic emission layer. The light source may also include LEDs and, if desired, a light guide panel.

Non-limiting examples of a display device (e.g., a liquid crystal display device) according to embodiments are illustrated with reference to the accompanying drawings. Fig. 4 is a schematic sectional view illustrating a liquid crystal display according to an embodiment. The display device of the embodiment includes a liquid crystal panel 200, a polarizer 300 disposed under the liquid crystal panel 200, and a backlight unit (BLU) disposed under the polarizer 300.

The liquid crystal panel 200 includes a lower substrate 210, a stack structure, and a liquid crystal layer 220 disposed between the stack structure and the lower substrate. The stacked structure includes a transparent substrate (or upper substrate) 240 and a photoluminescent layer 230 including a pattern including a quantum dot-polymer composite.

The lower substrate 210 (also referred to as an array substrate) may be a transparent insulating material substrate. The substrate is the same as described above. A wiring board 211 is disposed on the upper surface of the lower substrate 210. The wiring board 211 may include a plurality of gate lines and a plurality of data lines defining pixel regions, a thin film transistor disposed adjacent to an intersection region of the gate lines and the data lines, and a pixel electrode for each pixel region, but is not limited thereto. The details of such wiring boards are known and not particularly limited.

The liquid crystal layer 220 may be disposed on the wiring board 211. The liquid crystal panel 200 may include alignment layers 221 on and under the liquid crystal layer 220 to initially align liquid crystal materials included therein. Details of the liquid crystal material and the alignment layer (e.g., liquid crystal material, alignment layer material, method of forming the liquid crystal layer, thickness of the liquid crystal layer, etc.) are known and are not particularly limited.

The lower polarizer 300 is disposed under the lower substrate. The material and structure of the polarizer 300 are known and not particularly limited. A backlight unit (e.g., emitting blue light) may be disposed under the polarizer 300.

The upper optical element (or upper polarizer) 300 may be disposed between the liquid crystal layer 220 and the transparent substrate 240, but is not limited thereto. For example, the upper polarizer may be disposed between the liquid crystal layer 220 and the photoluminescent layer 230. The polarizer may be any polarizer used in a liquid crystal display device. The polarizer may be TAC (triacetyl cellulose) having a thickness of less than or equal to about 200 μm, but is not limited thereto. In an embodiment, the upper optical element may be a coating that controls the refractive index without a polarizing function.

The backlight unit includes a light source 110. The light source may emit blue or white light. The light source may include a blue (or green) LED, a white OLED, or a combination thereof, but is not limited thereto.

The backlight unit may further include a light guide panel 120. In an embodiment, the backlight unit may be an edge-light type illumination. For example, the backlight unit may include a reflector, a light guide panel disposed on the reflector and providing a planar light source to the liquid crystal panel 200, at least one optical sheet (e.g., a diffusion plate, a prism sheet, etc.) positioned on the light guide panel, or a combination thereof, but is not limited thereto. The backlight unit may not include a light guide panel. In an embodiment, the backlight unit may be a direct illumination. For example, the backlight unit may have a reflector, and may have a plurality of fluorescent lamps disposed on the reflector at regular intervals, or may have an LED-operating substrate on which a plurality of light emitting diodes may be disposed, a diffusion plate on the LED-operating substrate, and optionally at least one optical sheet. Details of such a backlight unit (e.g., each component of a light emitting diode, a fluorescent lamp, a light guide panel, various optical sheets, and a reflector) are known, and are not particularly limited.

The black matrix 241 is disposed under the transparent substrate 240 and has an opening, and hides gate lines, data lines, and thin film transistors of a wiring board located on a lower substrate. For example, the black matrix 241 may have a grid shape. The photoluminescent layer 230 is disposed in the opening of the black matrix 241 and has a quantum dot-polymer composite pattern including a first portion (R) configured to emit first light (e.g., red light), a second portion (G) configured to emit second light (e.g., green light), and a third portion (B) configured to emit/transmit, for example, blue light. The photoluminescent layer may also include at least one fourth portion, if desired. The fourth portion may include quantum dots emitting light (e.g., cyan light, magenta light, and yellow light) having a color different from that of the light emitted from the first to third portions.

In the photo-luminescent layer 230, a portion where a pattern is formed may be repeated corresponding to a pixel region formed on the lower substrate. A transparent common electrode 231 may be disposed on the photo-luminescent layer 230 (e.g., a photo-luminescent color filter layer).

The third portion (B) configured to emit and/or transmit excitation light or a portion thereof (e.g., blue light) may be a transparent color filter that does not change the emission spectrum of the light source. In this case, blue light emitted from the backlight unit may enter in a polarized state and may be emitted through the polarizer and the liquid crystal layer as it is. The third portion may include quantum dots that emit blue light, if desired.

The display device may also include an excitation light (blue, green, or a combination thereof) blocking layer (cut-off filter) or a first filter layer, if desired. The excitation light blocking layer may be disposed between the bottom surfaces of the first portion (R), the second portion (G), and the optional third portion (B) and the upper substrate 240 or on the top surface of the upper substrate 240. The excitation light (blue) blocking layer may include a sheet having an opening corresponding to a pixel region (e.g., a third portion) displaying blue. In an embodiment, the excitation light may further include green and blue light, and the third portion (e.g., blue pixel) may further include a green light cut-off layer. The excitation light blocking layer may be formed on portions corresponding to the first and second portions and the optional third portion. The first filter layer may be integrally formed as a unitary structure at a portion other than the portion overlapping the third portion, but is not limited thereto. At least two (e.g., three) first filter layers may be spaced apart and disposed at each location overlying the first and second portions and the optional third portion.

In an embodiment, the first filter layer may block light having a portion of a wavelength region in a visible light region. The first filter layer may transmit light having other (visible) wavelength regions. For example, the first filter layer may block blue (or green) light and transmit light other than the blue (or green) light. For example, the first filter layer may transmit green light, red light, and/or yellow light as a mixture of green and red light. The first filter layer may transmit blue light and block green light, and may be disposed on the blue light emitting pixels.

In an embodiment, the first filter layer may substantially block blue light having a wavelength less than or equal to about 500 nm. The first filter layer may transmit light of another visible wavelength region greater than or equal to about 500nm and less than or equal to about 700 nm.

In embodiments, the first filter layer may have a light transmittance of greater than or equal to about 70%, greater than or equal to about 80%, greater than or equal to about 90%, or even about 100% with respect to visible light of a desired wavelength range (e.g., may be selected from about 500nm to about 700 nm).

The first filter layer may include a polymer film including a dye, a pigment, or a combination thereof that absorbs light having a wavelength to be blocked. The first filter layer may block at least 80% (or at least 90%, even at least 95%) of the excitation light (e.g., having a wavelength less than or equal to about 480 nm), and the first filter layer may have a light transmittance of greater than or equal to about 70%, greater than or equal to about 80%, greater than or equal to about 90%, or even about 100% with respect to visible light of a desired wavelength range (e.g., selected from greater than or equal to about 500nm and less than or equal to about 700 nm).

The first filter layer may block (e.g., absorb) and substantially block excitation light or a portion of excitation light (e.g., green light or blue light having a wavelength less than or equal to about 500nm, or a combination thereof), and may, for example, selectively transmit light of a desired wavelength (e.g., green or red light or optionally blue light). In this case, at least two first filter layers may be spaced apart and disposed on each portion overlapping the first portion and the second portion, respectively. For example, a first filter layer selectively transmitting red light may be disposed on a portion overlapping with a portion emitting red light, and a first filter layer selectively transmitting green light may be disposed on a portion overlapping with a portion emitting green light, respectively. The first filter layer selectively transmitting blue light may be disposed on a portion overlapping the portion emitting blue light.

In embodiments, the first filter layer may include at least one of a first region that blocks (e.g., absorbs) blue and red light and transmits light having a predetermined range of wavelengths (e.g., greater than or equal to about 500nm, greater than or equal to about 510nm, or greater than or equal to about 515nm and less than or equal to about 550nm, less than or equal to about 545nm, less than or equal to about 540nm, less than or equal to about 535nm, less than or equal to about 530nm, less than or equal to about 525nm, or less than or equal to about 520nm), and a second region that blocks (e.g., absorbs) blue and green light and transmits light having a predetermined range of wavelengths (e.g., greater than or equal to about 600nm, greater than or equal to about 610nm, or greater than or equal to about 615nm and less than or equal to about 650nm, less than or equal to about 645nm, or equal to about 645 nm), Less than or equal to about 640nm, less than or equal to about 635nm, less than or equal to about 630nm, less than or equal to about 625nm, or less than or equal to about 620 nm). The first region may be disposed at a position overlapping with the portion emitting green light, and the second region may be disposed at a position overlapping with the portion emitting red light. When the excitation light includes green light, a first filter layer that blocks (or absorbs) green light may be disposed on the blue light emitting portion.

The first region and the second region may be optically isolated. The first filter layer may help to improve the color purity of the display device.

The first filter layer may be a reflective filter including a plurality of layers (e.g., inorganic material layers) having different refractive indices. For example, two layers having different refractive indices may be alternately stacked on each other, or, for example, a layer having a high refractive index and a layer having a low refractive index may be alternately stacked on each other.

When the refractive index difference between the layer having a high refractive index and the layer having a low refractive index is larger, the first filter layer having higher wavelength selectivity may be provided. The thickness and the number of stacks of the layer having the high refractive index and the layer having the low refractive index may be determined according to the refractive index and the reflection wavelength of each layer, for example, each layer having the high refractive index may have a thickness of about 3nm to about 300nm, and each layer having the low refractive index may have a thickness of about 3nm to about 300 nm.

The total thickness of the first filter layer may be, for example, about 3nm to about 10000nm, about 300nm to about 10000nm, or about 1000nm to about 10000 nm. The high refractive index layers may have the same thickness, the same material, or a combination thereof as each other, or may have different thicknesses, different materials, or a combination thereof from each other. The low refractive index layers may have the same thickness, the same material, or a combination thereof as each other, or may have different thicknesses, different materials, or a combination thereof from each other.

The display device may further include a second filter layer 311 (e.g., a red/green (or yellow) light recycling layer), the second filter layer 311 being disposed between the photoluminescent layer and the liquid crystal layer (e.g., between the photoluminescent layer and the upper polarizer) and transmitting at least a portion of the third light and reflecting at least a portion of the first and second light. The second filter layer may reflect light in a wavelength region greater than about 500 nm. The first light may be red light, the second light may be green light, and the third light may be blue light.

In the display device according to the embodiment, the second filter layer may be formed as an integrated single layer having a substantially flat surface.

In embodiments, the second filter layer may include a single layer having a low refractive index, for example, the second filter layer may be a transparent thin film having a refractive index of less than or equal to about 1.4, less than or equal to about 1.3, or less than or equal to about 1.2.

The second filter layer having a low refractive index may be, for example, porous silicon oxide, a porous organic material, a porous organic/inorganic composite, or a combination thereof.

In embodiments, the second filter layer may include a plurality of layers having different refractive indices, for example, the second filter layer may be formed by alternately stacking two layers having different refractive indices, or for example, the second filter layer may be formed by alternately stacking a material having a high refractive index and a material having a low refractive index.

The layer having a high refractive index in the second filter layer may include, for example, at least one of hafnium oxide, tantalum oxide, titanium oxide, zirconium oxide, magnesium oxide, cesium oxide, lanthanum oxide, indium oxide, niobium oxide, aluminum oxide, and silicon nitride, but according to an embodiment, the layer having a high refractive index in the second filter layer may include various materials having a higher refractive index than that of the layer having a low refractive index.

The layer having a low refractive index in the second filter layer may include, for example, silicon oxide, but according to an embodiment, the layer having a low refractive index may include various materials having a refractive index lower than that of the layer having a high refractive index.

The second filter layer may have higher wavelength selectivity as the refractive index difference between the layer having a high refractive index and the layer having a low refractive index is larger.

In the second filter layer, respective thicknesses of the layer having a high refractive index and the layer having a low refractive index and the number of stacks thereof may be determined according to the refractive index and the reflection wavelength of each layer, for example, each layer having a high refractive index in the second filter layer may have a thickness of about 3nm to about 300nm, and each layer having a low refractive index in the second filter layer may have a thickness of about 3nm to about 300 nm. The total thickness of the second filter layer may be, for example, about 3nm to about 10000nm, about 300nm to about 10000nm, or about 1000nm to about 10000 nm. Each of the layer having a high refractive index and the layer having a low refractive index in the second filter layer may have the same thickness and material as each other or different thicknesses and materials from each other.

The second filter layer may reflect at least a portion of the first light (R) and the second light (G) and transmit at least a portion (e.g., all) of the third light (B). For example, the second filter layer may transmit only the third light (B) in a blue wavelength region less than or equal to about 500nm, while light in a wavelength region greater than about 500nm (i.e., green (G), yellow (G), red (R), etc.) may not pass through the second filter layer and be reflected. Accordingly, the reflected green and red light may pass through the first and second portions to be emitted to the outside of the display device.

The second filter layer may reflect greater than or equal to about 70%, greater than or equal to about 80%, or greater than or equal to about 90%, or even about 100% of light in a wavelength region greater than about 500 nm.

Meanwhile, the transmittance of the second filter layer to light in a wavelength region of less than or equal to about 500nm may be, for example, greater than or equal to about 90%, greater than or equal to about 92%, greater than or equal to about 94%, greater than or equal to about 96%, greater than or equal to about 98%, greater than or equal to about 99%, or even about 100%.

In an embodiment, the stacked structure may be manufactured by a method using a photoresist composition. The method may comprise the steps of: forming a film of the composition on a substrate; exposing selected regions of the film to light (e.g., at a wavelength of less than or equal to about 400 nm); and developing the exposed film with an alkali developing solution to obtain a pattern including the quantum dot-polymer composite.

The substrate and composition have the same specifications as those described above. A non-limiting method of forming the pattern is illustrated with reference to fig. 5.

The composition is coated on the substrate to have a predetermined thickness by a suitable method of spin coating, slit coating, or the like (S1). The formed film may optionally be pre-baked (PRB) (S2). The prebaking may be performed by selecting an appropriate condition from known conditions of temperature, time, atmosphere, and the like.

The formed (or optionally pre-baked) film is exposed to light having a predetermined wavelength under a mask having a predetermined pattern (S3). The wavelength and intensity of light may be selected in consideration of the type and amount of (photo) initiator, the type and amount of quantum dot, and the like.

The exposed film is treated (e.g., dipped or sprayed) using an alkali developing solution to dissolve the unexposed area and obtain a desired pattern (S4). The obtained pattern may optionally be post-baked (POB) for a predetermined time (e.g., greater than or equal to about 10 minutes or greater than or equal to about 20 minutes), for example, at about 150 ℃ to about 230 ℃, to improve crack and solvent resistance of the pattern (S5). The quantum dot-polymer composite including the quantum dot of the embodiment may exhibit an excitation light conversion rate of greater than about 29% (e.g., greater than or equal to about 30% or greater than or equal to about 31%).

In embodiments where the quantum dot-polymer composite pattern has multiple repeating portions, a quantum dot-polymer composite having a desired pattern can be obtained by: preparing a plurality of compositions comprising quantum dots having desired photoluminescence properties (photoluminescence peak wavelengths, etc.) to form each of the repeating portions (e.g., red-emitting quantum dots, green-emitting quantum dots, or optionally blue-emitting quantum dots); and repeating the formation of the above-described pattern for each composition an appropriate number of times (e.g., two or more times or three or more times) (S6). For example, the quantum dot-polymer composite may have (e.g., be disposed as) a pattern including at least two repeating color portions (e.g., RGB portions). The quantum dot-polymer composite pattern may be used as a photoluminescent type color filter in a display device.

In an embodiment, the stacked structure may be fabricated using an ink composition. The method may include depositing the ink composition (e.g., to provide a desired pattern) on a desired substrate using a suitable system (e.g., a drop discharge device such as an inkjet or nozzle printing device) and heating it to remove the solvent and polymerize. The method can provide a highly accurate quantum dot-polymer composite film or pattern in a simple and fast manner.

Embodiments provide an electronic device including the quantum dot. The device may include a Light Emitting Diode (LED), an Organic Light Emitting Diode (OLED), a sensor, a solar cell, an imaging sensor, or a Liquid Crystal Display (LCD), but is not limited thereto.

Hereinafter, other embodiments are explained in more detail with reference to the following examples. Note that examples represent exemplary embodiments of the present invention, and the present invention is not limited thereto.

Examples of the invention

Analytical method

1. Ultraviolet (UV) -visible (Vis) absorption analysis

UV-Vis spectroscopy was performed using a Shimadzu UV2700 spectrometer and UV-visible absorption spectra were obtained.

2. Photoluminescence analysis

Photoluminescence analysis was performed using a PL QY spectrometer Otsuka QE-2100 (available from tsukamur Electronics co., Ltd.) and a photoluminescence spectrum was obtained. Photoluminescence spectra of the produced nanocrystals were obtained at an irradiation wavelength of 450 nm.

3. ICP analysis

Inductively coupled plasma-atomic emission spectroscopy (ICP-AES) analysis was performed using Shimadzu ICPS-8100.

4. Brightness and luminous efficiency of quantum dot-polymer composite

The luminous efficiency of the excitation with blue excitation light (B) is measured using an integrating sphere using methods well known to those skilled in the art. The QD-polymer complex was placed in an integrating sphere and illuminated with blue excitation light. The amount of green (or red) light (a) emitted from the illuminated composite and the amount of blue light (B') passing through the composite are measured, respectively.

The blue light absorption rate and quantum efficiency of the quantum dot-polymer composite were obtained according to the following equations:

blue light absorptivity ═ (B-B')/B × 100%

Blue light conversion rate ═ A/B × 100%

B: intensity of blue excitation light (photon)

A: intensity of green (or red) light emitted from the composite during blue excitation

B': the intensity of the blue excitation light that passes through (or is not absorbed by) the composite.

With reference to example 1: the InZnP core was prepared in the following manner.

Indium acetate, zinc acetate and palmitic acid were dissolved in 1-octadecene in a 200 milliliter (mL) reaction flask and the mixture was heated under vacuum at 120 ℃ for 1 hour. The molar ratio of indium, zinc and palmitic acid added to the reaction flask was 1:1: 3. After 1 hour, nitrogen was slowly introduced into the reaction flask to about 1atm, the reaction flask was heated to 260 ℃, and tris (trimethylsilyl) phosphine (TMS) was then rapidly injected₃P) and Trioctylphosphine (TOP). TMS₃The amount of P is about 0.75 mole per 1 mole of indium. The reaction mixture was held at about 260 ℃ for about 20 minutes. The reaction mixture was then rapidly cooled to room temperature and acetone was added to the reaction mixture to promote precipitation of the nanocrystals, which were then separated by centrifugation and dispersed in toluene to obtain a toluene dispersion of nanocrystals of the InZnP core. The average particle size of the InZnP core is about 2 nanometers (nm).

Example 1:

[1] synthesis of quantum dots and characterization thereof

(1) Selenium and sulfur were dispersed in Trioctylphosphine (TOP) to obtain 2 molar (M) Se/TOP stock solutions and 2M S/TOP stock solutions, respectively.

In a 200mL reaction flask, zinc acetate and oleic acid were dissolved in trioctylamine and the solution was heated under vacuum at 120 ℃ for 10 minutes. After 10 minutes, nitrogen was slowly added to the reaction flask to about 1atm and the resulting solution was heated to about 320 ℃. The toluene dispersion of the InZnP semiconductor nanocrystal cores prepared in reference example 1 was injected into a reaction flask, and several predetermined amounts of Se/TOP stock solution were injected into the reaction flask over time. A reaction is performed to obtain a reaction mixture comprising nanoparticles having a ZnSe shell disposed on an InZnP core. The total reaction time was 100 minutes, and the total amount of Se used was about 20 moles per 1 mole of indium.

Thereafter, the 2M S/TOP stock solution was slowly injected into the reaction mixture over the reaction time with the reaction mixture maintained at 320 ℃ to obtain a resulting solution comprising particles having a ZnS shell disposed over a ZnSe shell. The total reaction time was 40 minutes, and the total amount of S used was about 12 moles per 1 mole of indium.

Excess ethanol was added to the final reaction mixture to promote the deposition of InZnP/ZnSe/ZnS semiconductor nanocrystals, which were then centrifuged. After centrifugation, the supernatant was discarded, and the separated nanocrystals were dried and dispersed in chloroform or toluene to obtain a quantum dot solution (hereinafter, referred to as a QD solution). The QD solution was subjected to ICP-AES analysis, and the results are shown in table 1. The QD solution was also subjected to UV-vis absorption spectroscopy and photoluminescence spectroscopy, and the results are shown in table 1.

[2] Fabrication of quantum dot-polymer composites and patterns thereof.

(1) Preparation of Quantum dot-adhesive Dispersion

The chloroform solution of the quantum dots prepared above was mixed with a solution of a binder polymer, which was a copolymer of methacrylic acid, benzyl methacrylate, hydroxyethyl methacrylate, and styrene (acid value: 130mg KOH per gram (mg KOH/g), molecular weight: 8000 g/mole (g/mol), methacrylic acid: benzyl methacrylate: hydroxyethyl methacrylate: styrene (molar ratio): 61.5:12:16.3: 10.2). Propylene Glycol Monomethyl Ether Acetate (PGMEA) was used as a solvent to provide a 30 weight percent (wt%) quantum dot-binder dispersion.

(2) Preparation of photosensitive composition

To the quantum dot-binder dispersion prepared above, hexaacrylate having the following structure (as a photopolymerizable monomer), ethylene glycol di-3-mercaptopropionate (hereinafter, referred to as 2T as a polythiol compound), oxime ester compound (as a photoinitiator), TiO were added₂(as metal oxide fine particles) and PGMEA (as solvent) to obtain a composition.

(ethylene glycol di-3-mercaptopropionate)

(Hexaacrylate)

Wherein the content of the first and second substances,

based on the total solid content, the prepared composition comprises 40 wt% of quantum dots, 12.5 wt% of binder polymer, 25 wt% of 2T, 12 wt% of photopolymerizable monomer, 0.5 wt% of photoinitiator and 10 wt% of TiO₂Fine particles. The total solids content was about 25 wt%.

(3) Quantum dot-polymer composite pattern formation and thermal treatment

The composition obtained above was spin-coated on a glass substrate at 150 revolutions per minute (rpm) for 5 seconds(s) to provide a film. The obtained film was pre-baked (PRB) at 100 ℃. The pre-baked film was exposed to light (wavelength: 365nm, intensity: 100 millijoules (mJ)) for 1 second under a mask having a predetermined pattern (e.g., a square dot or stripe pattern). The film was subjected to development using an aqueous potassium hydroxide solution (concentration: 0.043 weight percent) for 50 seconds to obtain a pattern of quantum dot-polymer composites having a thickness of 6 micrometers (μm).

The obtained pattern was heat-treated at a temperature of 180 ℃ for 30 minutes (POB) under a nitrogen atmosphere. For the obtained film pattern (QD example 1), the photoluminescence peak wavelength, the blue light absorbance, and the light conversion efficiency were measured, and the results are shown in table 2.

Example 2

1. The core-shell quantum dots of example 2 were prepared in the same manner as set forth in example 1, except that 1 mole of indium was used per 18 moles of Se. For the obtained QD solution, ICP-AES analysis, UV-vis absorption spectroscopy analysis, and photoluminescence spectroscopy were measured, and the results are shown in table 1.

2. A quantum dot-polymer composite was prepared in the same manner as set forth in example 1, except that the quantum dot obtained in example 2 was used (QD example 2). For the obtained film pattern, the blue light absorption rate and the light conversion efficiency were measured, and the results are shown in table 2.

Comparative example 1

1. InZnP/ZnSe/ZnS quantum dots were prepared in the same manner as set forth in example 1, except that 1 mole of indium was used per 7 moles of Se.

For the obtained QD solution, ICP-AES analysis, UV-vis absorption spectroscopy analysis, and photoluminescence spectroscopy analysis were performed, and the results are shown in table 1.

2. A quantum dot-polymer composite was prepared in the same manner as set forth in example 1, except that the quantum dot obtained in comparative example 1 was used (QD comparative example 1). For the obtained film pattern, the blue light absorption rate and the light conversion efficiency were measured, and the results are shown in table 2.

Comparative example 2

1. The InZnP/ZnSe/ZnS quantum dots were prepared in the same manner as set forth in example 1, except that the ZnS coating was prepared by employing a rapid injection manner (i.e., a process in which the S/TOP stock solution (e.g., within one minute) was injected into the reaction flask in a single portion rather than in several different portions over the course of several tens of minutes as in example 1 (i.e., the S/TOP stock solution was provided by rapid injection).

2. A quantum dot-polymer composite was prepared in the same manner as set forth in example 1, except that the quantum dot obtained in comparative example 2 was used (QD comparative example 2). For the obtained film pattern, the blue light absorption rate and the light conversion efficiency were measured, and the results are shown in table 2.

TABLE 1

TABLE 2

The results and data reported in table 2 confirm that the quantum dot-polymer composites (QD example 1 and QD example 2) including the quantum dots of examples 1 to 2, respectively, exhibit enhanced optical properties and stability (process retention) compared to the quantum dot-polymer composites (QD comparative example 1 and QD comparative example 2) including the quantum dots of comparative example 1 and comparative example 2, respectively.

While the disclosure has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

1. A quantum dot, comprising:

a semiconductor nanocrystal core comprising indium and phosphorus,

a semiconductor nanocrystal shell disposed on the semiconductor nanocrystal core, the semiconductor nanocrystal shell comprising zinc, selenium, and sulfur,

wherein the quantum dot has a maximum photoluminescence peak in a green wavelength region, and a ratio A of an absorption value at 450nm to an absorption value of a first absorption peak in an ultraviolet-visible absorption spectrum of the quantum dot₄₅₀/A_firstGreater than or equal to 0.7, and a valley depth VD defined by the following equation is greater than or equal to 0.4:

(Abs_first-Abs_valley)/Abs_first＝VD

wherein the quantum dots do not include cadmium.

2. The quantum dot of claim 1, wherein the semiconductor nanocrystal core further comprises zinc.

3. The quantum dot of claim 1, wherein a molar ratio of sulfur to selenium in the quantum dot is less than or equal to 2.5: 1.

4. The quantum dot of claim 1, wherein a molar ratio of sulfur to selenium in the quantum dot is less than or equal to 0.8: 1.

5. The quantum dot of claim 1, wherein a molar ratio of zinc to indium in the quantum dot is greater than or equal to 10:1 and less than or equal to 50: 1.

6. The quantum dot of claim 1, wherein a molar ratio of the sum of selenium and sulfur to indium in the quantum dot is greater than or equal to 10:1 and less than or equal to 40: 1.

7. The quantum dot of claim 1, wherein a molar ratio of the sum of selenium and sulfur to indium in the quantum dot is greater than or equal to 20:1 and less than or equal to 38: 1.

8. The quantum dot of claim 1, wherein the semiconductor nanocrystal shell comprises: a first shell comprising zinc and selenium; and a second shell disposed on the first shell and including zinc and sulfur.

9. The quantum dot of claim 8, wherein the second shell layer does not include selenium and the second shell layer is an outermost layer of the quantum dot.

10. The quantum dot of claim 1, wherein the green wavelength region is greater than or equal to 500 nanometers and less than or equal to 560 nanometers.

11. The quantum dot of claim 1, wherein a molar ratio of zinc to indium in the quantum dot is greater than or equal to 26:1 and less than or equal to 45: 1.

12. The quantum dot of claim 1, wherein the first absorption peak is in a wavelength range greater than 450 nanometers and less than or equal to a wavelength of the maximum photoluminescence peak.

13. The quantum dot of claim 12, wherein the first absorption peak is in a wavelength range of greater than or equal to 455 nanometers.

14. The quantum dot of claim 1, wherein a valley adjacent to the first absorption peak exists in a range of greater than or equal to 420 nanometers and less than or equal to 490 nanometers.

15. The quantum dot of claim 1, wherein a ratio of an absorption value at 450 nanometers to an absorption value at the first absorption peak is greater than or equal to 0.75.

16. The quantum dot of claim 1, wherein the valley depth is greater than or equal to 0.5.

17. The quantum dot of claim 1, wherein the quantum dot is present as a plurality of quantum dots having an average size greater than or equal to 4 nanometers and less than or equal to 8 nanometers and a standard deviation of less than or equal to 30% of the average size.

18. The quantum dot of claim 1, wherein a maximum photoluminescence peak of the quantum dot exhibits a full width at half maximum of less than or equal to 50 nanometers.

19. The quantum dot of claim 1, wherein the quantum efficiency of the quantum dot is greater than or equal to 84%.

20. A quantum dot-polymer composite, the quantum dot-polymer composite comprising:

a polymer matrix; and

a plurality of quantum dots dispersed in a polymer matrix, wherein the plurality of quantum dots comprises the quantum dot of any one of claims 1-19.

21. The quantum dot-polymer composite of claim 20, wherein the quantum dot-polymer composite comprises a blue light conversion of greater than or equal to 29% after being heat treated at a temperature of 180 ℃ for 30 minutes.

22. The quantum dot-polymer composite of claim 20 or 21, wherein the polymer matrix comprises a crosslinked polymer, a linear polymer with carboxylic acid groups, or a combination thereof.

23. The quantum dot-polymer composite of claim 22, wherein the crosslinked polymer comprises a polymerization product of a monomer having at least two carbon-carbon double bonds, a polymerization product of the monomer and a polythiol compound comprising at least two thiol groups, or a combination thereof.

24. The quantum dot-polymer composite of claim 20 or 21, further comprising metal oxide fine particles dispersed in a polymer matrix.

25. A display device, the display device comprising:

a light source and a light-emitting element,

wherein the light emitting element comprises the quantum dot-polymer composite according to any one of claims 20 to 24, and the light source provides incident light to the light emitting element.

26. The display device of claim 25, wherein the incident light has a luminescence peak wavelength of 440 to 460 nanometers.

27. A display device according to claim 25 or 26, wherein the light-emitting element comprises a sheet comprising a quantum dot-polymer composite.

28. The display device according to claim 25 or 26, wherein the light-emitting element comprises a stacked structure including a substrate and a light-emitting layer provided over the substrate,

wherein the light emitting layer comprises a pattern comprising a quantum dot-polymer composite.

29. The display device according to claim 25 or 26, wherein the display device exhibits color reproducibility of greater than or equal to 80% based on BT 2020.